# class String

A `String` object holds and manipulates an arbitrary sequence of bytes, typically representing characters. `String` objects may be created using `String::new` or as literals.

Because of aliasing issues, users of strings should be aware of the methods that modify the contents of a `String` object. Typically, methods with names ending in “!'' modify their receiver, while those without a “!'' return a new `String`. However, there are exceptions, such as `String#[]=`.

### Public Class Methods

new(string = '') → new_string click to toggle source
new(string = '', encoding: encoding) → new_string
new(string = '', capacity: size) → new_string

Returns a new String that is a copy of `string`.

With no arguments, returns the empty string with the `Encoding` `ASCII-8BIT`:

    s = String.new
    s # => ""
    s.encoding # => #<Encoding:ASCII-8BIT>

With the single String argument `string`, returns a copy of `string` with the same encoding as `string`:

    s = String.new("Que veut dire \u{e7}a?")
    s # => "Que veut dire \u{e7}a?"
    s.encoding # => #<Encoding:UTF-8>

Literal strings like `""` or here-documents always use script encoding, unlike `String.new`.

With keyword `encoding`, returns a copy of `str` with the specified encoding:

    s = String.new(encoding: 'ASCII')
    s.encoding # => #<Encoding:US-ASCII>
    s = String.new('foo', encoding: 'ASCII')
    s.encoding # => #<Encoding:US-ASCII>

Note that these are equivalent:

    s0 = String.new('foo', encoding: 'ASCII')
    s1 = 'foo'.force_encoding('ASCII')
    s0.encoding == s1.encoding # => true

With keyword `capacity`, returns a copy of `str`; the given `capacity` may set the size of the internal buffer, which may affect performance:

    String.new(capacity: 1) # => ""
    String.new(capacity: 4096) # => ""

The `string`, `encoding`, and `capacity` arguments may all be used together:

    String.new('hello', encoding: 'UTF-8', capacity: 25)

    static VALUE
    rb_str_init(int argc, VALUE *argv, VALUE str)
    {
        static ID keyword_ids[2];
        VALUE orig, opt, venc, vcapa;
        VALUE kwargs[2];
        rb_encoding *enc = 0;
        int n;

        if (!keyword_ids[0]) {
            keyword_ids[0] = rb_id_encoding();
            CONST_ID(keyword_ids[1], "capacity");
        }

        n = rb_scan_args(argc, argv, "01:", &orig, &opt);
        if (!NIL_P(opt)) {
            rb_get_kwargs(opt, keyword_ids, 0, 2, kwargs);
            venc = kwargs[0];
            vcapa = kwargs[1];
            if (venc != Qundef && !NIL_P(venc)) {
                enc = rb_to_encoding(venc);
            }
            if (vcapa != Qundef && !NIL_P(vcapa)) {
                long capa = NUM2LONG(vcapa);
                long len = 0;
                int termlen = enc ? rb_enc_mbminlen(enc) : 1;

                if (capa < STR_BUF_MIN_SIZE) {
                    capa = STR_BUF_MIN_SIZE;
                }
                if (n == 1) {
                    StringValue(orig);
                    len = RSTRING_LEN(orig);
                    if (capa < len) {
                        capa = len;
                    }
                    if (orig == str) n = 0;
                }
                str_modifiable(str);
                if (STR_EMBED_P(str)) { /* make noembed always */
                    char *new_ptr = ALLOC_N(char, (size_t)capa + termlen);
                    memcpy(new_ptr, RSTRING(str)->as.ary, RSTRING_EMBED_LEN_MAX + 1);
                    RSTRING(str)->as.heap.ptr = new_ptr;
                }
                else if (FL_TEST(str, STR_SHARED|STR_NOFREE)) {
                    const size_t size = (size_t)capa + termlen;
                    const char *const old_ptr = RSTRING_PTR(str);
                    const size_t osize = RSTRING(str)->as.heap.len + TERM_LEN(str);
                    char *new_ptr = ALLOC_N(char, (size_t)capa + termlen);
                    memcpy(new_ptr, old_ptr, osize < size ? osize : size);
                    FL_UNSET_RAW(str, STR_SHARED);
                    RSTRING(str)->as.heap.ptr = new_ptr;
                }
                else if (STR_HEAP_SIZE(str) != (size_t)capa + termlen) {
                    SIZED_REALLOC_N(RSTRING(str)->as.heap.ptr, char,
                            (size_t)capa + termlen, STR_HEAP_SIZE(str));
                }
                RSTRING(str)->as.heap.len = len;
                TERM_FILL(&RSTRING(str)->as.heap.ptr[len], termlen);
                if (n == 1) {
                    memcpy(RSTRING(str)->as.heap.ptr, RSTRING_PTR(orig), len);
                    rb_enc_cr_str_exact_copy(str, orig);
                }
                FL_SET(str, STR_NOEMBED);
                RSTRING(str)->as.heap.aux.capa = capa;
            }
            else if (n == 1) {
                rb_str_replace(str, orig);
            }
            if (enc) {
                rb_enc_associate(str, enc);
                ENC_CODERANGE_CLEAR(str);
            }
        }
        else if (n == 1) {
            rb_str_replace(str, orig);
        }
        return str;
    }

try_convert(object) → object, new_string, or nil click to toggle source

If `object` is a String object, returns `object`.

Otherwise if `object` responds to `:to_str`, calls `object.to_str` and returns the result.

Returns `nil` if `object` does not respond to `:to_str`

Raises an exception unless `object.to_str` returns a String object.

    static VALUE
    rb_str_s_try_convert(VALUE dummy, VALUE str)
    {
        return rb_check_string_type(str);
    }

### Public Instance Methods

string % object → new_string click to toggle source

Returns the result of formatting `object` into the format specification `self` (see `Kernel#sprintf` for formatting details):

    "%05d" % 123 # => "00123"

If `self` contains multiple substitutions, `object` must be an Array or Hash containing the values to be substituted:

    "%-5s: %016x" % [ "ID", self.object_id ] # => "ID   : 00002b054ec93168"
    "foo = %{foo}" % {foo: 'bar'} # => "foo = bar"
    "foo = %{foo}, baz = %{baz}" % {foo: 'bar', baz: 'bat'} # => "foo = bar, baz = bat"

    static VALUE
    rb_str_format_m(VALUE str, VALUE arg)
    {
        VALUE tmp = rb_check_array_type(arg);

        if (!NIL_P(tmp)) {
            return rb_str_format(RARRAY_LENINT(tmp), RARRAY_CONST_PTR(tmp), str);
        }
        return rb_str_format(1, &arg, str);
    }

string * integer → new_string click to toggle source

Returns a new String containing `integer` copies of `self`:

    "Ho! " * 3 # => "Ho! Ho! Ho! "
    "Ho! " * 0 # => ""

    VALUE
    rb_str_times(VALUE str, VALUE times)
    {
        VALUE str2;
        long n, len;
        char *ptr2;
        int termlen;

        if (times == INT2FIX(1)) {
            return str_duplicate(rb_cString, str);
        }
        if (times == INT2FIX(0)) {
            str2 = str_alloc(rb_cString);
            rb_enc_copy(str2, str);
            return str2;
        }
        len = NUM2LONG(times);
        if (len < 0) {
            rb_raise(rb_eArgError, "negative argument");
        }
        if (RSTRING_LEN(str) == 1 && RSTRING_PTR(str)[0] == 0) {
           str2 = str_alloc(rb_cString);
           if (!STR_EMBEDDABLE_P(len, 1)) {
               RSTRING(str2)->as.heap.aux.capa = len;
               RSTRING(str2)->as.heap.ptr = ZALLOC_N(char, (size_t)len + 1);
               STR_SET_NOEMBED(str2);
           }
           STR_SET_LEN(str2, len);
           rb_enc_copy(str2, str);
           return str2;
        }
        if (len && LONG_MAX/len <  RSTRING_LEN(str)) {
            rb_raise(rb_eArgError, "argument too big");
        }

        len *= RSTRING_LEN(str);
        termlen = TERM_LEN(str);
        str2 = str_new0(rb_cString, 0, len, termlen);
        ptr2 = RSTRING_PTR(str2);
        if (len) {
            n = RSTRING_LEN(str);
            memcpy(ptr2, RSTRING_PTR(str), n);
            while (n <= len/2) {
                memcpy(ptr2 + n, ptr2, n);
                n *= 2;
            }
            memcpy(ptr2 + n, ptr2, len-n);
        }
        STR_SET_LEN(str2, len);
        TERM_FILL(&ptr2[len], termlen);
        rb_enc_cr_str_copy_for_substr(str2, str);

        return str2;
    }

string + other_string → new_string click to toggle source

Returns a new String containing `other_string` concatenated to `self`:

    "Hello from " + self.to_s # => "Hello from main"

    VALUE
    rb_str_plus(VALUE str1, VALUE str2)
    {
        VALUE str3;
        rb_encoding *enc;
        char *ptr1, *ptr2, *ptr3;
        long len1, len2;
        int termlen;

        StringValue(str2);
        enc = rb_enc_check_str(str1, str2);
        RSTRING_GETMEM(str1, ptr1, len1);
        RSTRING_GETMEM(str2, ptr2, len2);
        termlen = rb_enc_mbminlen(enc);
        if (len1 > LONG_MAX - len2) {
            rb_raise(rb_eArgError, "string size too big");
        }
        str3 = str_new0(rb_cString, 0, len1+len2, termlen);
        ptr3 = RSTRING_PTR(str3);
        memcpy(ptr3, ptr1, len1);
        memcpy(ptr3+len1, ptr2, len2);
        TERM_FILL(&ptr3[len1+len2], termlen);

        ENCODING_CODERANGE_SET(str3, rb_enc_to_index(enc),
                               ENC_CODERANGE_AND(ENC_CODERANGE(str1), ENC_CODERANGE(str2)));
        RB_GC_GUARD(str1);
        RB_GC_GUARD(str2);
        return str3;
    }

+string → new_string or self click to toggle source

Returns `self` if `self` is not frozen.

Otherwise. returns `self.dup`, which is not frozen.

    static VALUE
    str_uplus(VALUE str)
    {
        if (OBJ_FROZEN(str)) {
            return rb_str_dup(str);
        }
        else {
            return str;
        }
    }

-string → frozen_string click to toggle source

Returns a frozen, possibly pre-existing copy of the string.

The returned String will be deduplicated as long as it does not have any instance variables set on it.

    static VALUE
    str_uminus(VALUE str)
    {
        if (!BARE_STRING_P(str) && !rb_obj_frozen_p(str)) {
            str = rb_str_dup(str);
        }
        return rb_fstring(str);
    }

string << object → str click to toggle source

Returns a new String containing the concatenation of `self` and `object`:

    s = 'foo'
    s << 'bar' # => "foobar"

If `object` is an Integer, the value is considered a codepoint and converted to a character before concatenation:

    s = 'foo'
    s << 33 # => "foo!"

Related: `String#concat`, which takes multiple arguments.

    VALUE
    rb_str_concat(VALUE str1, VALUE str2)
    {
        unsigned int code;
        rb_encoding *enc = STR_ENC_GET(str1);
        int encidx;

        if (RB_INTEGER_TYPE_P(str2)) {
            if (rb_num_to_uint(str2, &code) == 0) {
            }
            else if (FIXNUM_P(str2)) {
                rb_raise(rb_eRangeError, "%ld out of char range", FIX2LONG(str2));
            }
            else {
                rb_raise(rb_eRangeError, "bignum out of char range");
            }
        }
        else {
            return rb_str_append(str1, str2);
        }

        encidx = rb_enc_to_index(enc);
        if (encidx == ENCINDEX_ASCII || encidx == ENCINDEX_US_ASCII) {
            /* US-ASCII automatically extended to ASCII-8BIT */
            char buf[1];
            buf[0] = (char)code;
            if (code > 0xFF) {
                rb_raise(rb_eRangeError, "%u out of char range", code);
            }
            rb_str_cat(str1, buf, 1);
            if (encidx == ENCINDEX_US_ASCII && code > 127) {
                rb_enc_associate_index(str1, ENCINDEX_ASCII);
                ENC_CODERANGE_SET(str1, ENC_CODERANGE_VALID);
            }
        }
        else {
            long pos = RSTRING_LEN(str1);
            int cr = ENC_CODERANGE(str1);
            int len;
            char *buf;

            switch (len = rb_enc_codelen(code, enc)) {
              case ONIGERR_INVALID_CODE_POINT_VALUE:
                rb_raise(rb_eRangeError, "invalid codepoint 0x%X in %s", code, rb_enc_name(enc));
                break;
              case ONIGERR_TOO_BIG_WIDE_CHAR_VALUE:
              case 0:
                rb_raise(rb_eRangeError, "%u out of char range", code);
                break;
            }
            buf = ALLOCA_N(char, len + 1);
            rb_enc_mbcput(code, buf, enc);
            if (rb_enc_precise_mbclen(buf, buf + len + 1, enc) != len) {
                rb_raise(rb_eRangeError, "invalid codepoint 0x%X in %s", code, rb_enc_name(enc));
            }
            rb_str_resize(str1, pos+len);
            memcpy(RSTRING_PTR(str1) + pos, buf, len);
            if (cr == ENC_CODERANGE_7BIT && code > 127)
                cr = ENC_CODERANGE_VALID;
            ENC_CODERANGE_SET(str1, cr);
        }
        return str1;
    }

string <=> other_string → -1, 0, 1, or nil click to toggle source

Compares `self` and `other_string`, returning:

- -1 if `other_string` is smaller.

- 0 if the two are equal.

- 1 if `other_string` is larger.

- `nil` if the two are incomparable.

Examples:

    'foo' <=> 'foo' # => 0
    'foo' <=> 'food' # => -1
    'food' <=> 'foo' # => 1
    'FOO' <=> 'foo' # => -1
    'foo' <=> 'FOO' # => 1
    'foo' <=> 1 # => nil

    static VALUE
    rb_str_cmp_m(VALUE str1, VALUE str2)
    {
        int result;
        VALUE s = rb_check_string_type(str2);
        if (NIL_P(s)) {
            return rb_invcmp(str1, str2);
        }
        result = rb_str_cmp(str1, s);
        return INT2FIX(result);
    }

string == object → true or false click to toggle source

Returns `true` if `object` has the same length and content; as `self`; `false` otherwise:

    s = 'foo'
    s == 'foo' # => true
    s == 'food' # => false
    s == 'FOO' # => false

Returns `false` if the two strings' encodings are not compatible:

    "\u{e4 f6 fc}".encode("ISO-8859-1") == ("\u{c4 d6 dc}") # => false

If `object` is not an instance of String but responds to `to_str`, then the two strings are compared using `object.==`.

    VALUE
    rb_str_equal(VALUE str1, VALUE str2)
    {
        if (str1 == str2) return Qtrue;
        if (!RB_TYPE_P(str2, T_STRING)) {
            if (!rb_respond_to(str2, idTo_str)) {
                return Qfalse;
            }
            return rb_equal(str2, str1);
        }
        return rb_str_eql_internal(str1, str2);
    }

Also aliased as: ===
string === object → true or false

Returns `true` if `object` has the same length and content; as `self`; `false` otherwise:

    s = 'foo'
    s == 'foo' # => true
    s == 'food' # => false
    s == 'FOO' # => false

Returns `false` if the two strings' encodings are not compatible:

    "\u{e4 f6 fc}".encode("ISO-8859-1") == ("\u{c4 d6 dc}") # => false

If `object` is not an instance of String but responds to `to_str`, then the two strings are compared using `object.==`.

Alias for: ==
string =~ regexp → integer or nil click to toggle source
string =~ object → integer or nil

Returns the Integer index of the first substring that matches the given `regexp`, or `nil` if no match found:

    'foo' =~ /f/ # => 0
    'foo' =~ /o/ # => 1
    'foo' =~ /x/ # => nil

Note: also updates Regexp-related global variables.

If the given `object` is not a Regexp, returns the value returned by `object =~ self`.

Note that `string =~ regexp` is different from `regexp =~ string` (see Regexp#=~):

    number= nil
    "no. 9" =~ /(?<number>\d+)/
    number # => nil (not assigned)
    /(?<number>\d+)/ =~ "no. 9"
    number #=> "9"

    static VALUE
    rb_str_match(VALUE x, VALUE y)
    {
        switch (OBJ_BUILTIN_TYPE(y)) {
          case T_STRING:
            rb_raise(rb_eTypeError, "type mismatch: String given");

          case T_REGEXP:
            return rb_reg_match(y, x);

          default:
            return rb_funcall(y, idEqTilde, 1, x);
        }
    }

string[index] → new_string or nil click to toggle source
string[start, length] → new_string or nil
string[range] → new_string or nil
string[regexp, capture = 0] → new_string or nil
string[substring] → new_string or nil

Returns the substring of `self` specified by the arguments.

When the single Integer argument `index` is given, returns the 1-character substring found in `self` at offset `index`:

    'bar'[2] # => "r"

Counts backward from the end of `self` if `index` is negative:

    'foo'[-3] # => "f"

Returns `nil` if `index` is out of range:

    'foo'[3] # => nil
    'foo'[-4] # => nil

When the two Integer arguments `start` and `length` are given, returns the substring of the given `length` found in `self` at offset `start`:

    'foo'[0, 2] # => "fo"
    'foo'[0, 0] # => ""

Counts backward from the end of `self` if `start` is negative:

    'foo'[-2, 2] # => "oo"

Special case: returns a new empty String if `start` is equal to the length of `self`:

    'foo'[3, 2] # => ""

Returns `nil` if `start` is out of range:

    'foo'[4, 2] # => nil
    'foo'[-4, 2] # => nil

Returns the trailing substring of `self` if `length` is large:

    'foo'[1, 50] # => "oo"

Returns `nil` if `length` is negative:

    'foo'[0, -1] # => nil

When the single Range argument `range` is given, derives `start` and `length` values from the given `range`, and returns values as above:

- `'foo'[0..1]` is equivalent to `'foo'[0, 2]`.

- `'foo'[0...1]` is equivalent to `'foo'[0, 1]`.

When the Regexp argument `regexp` is given, and the `capture` argument is `0`, returns the first matching substring found in `self`, or `nil` if none found:

    'foo'[/o/] # => "o"
    'foo'[/x/] # => nil
    s = 'hello there'
    s[/[aeiou](.)\1/] # => "ell"
    s[/[aeiou](.)\1/, 0] # => "ell"

If argument `capture` is given and not `0`, it should be either an Integer capture group index or a String or Symbol capture group name; the method call returns only the specified capture (see Regexp Capturing):

    s = 'hello there'
    s[/[aeiou](.)\1/, 1] # => "l"
    s[/(?<vowel>[aeiou])(?<non_vowel>[^aeiou])/, "non_vowel"] # => "l"
    s[/(?<vowel>[aeiou])(?<non_vowel>[^aeiou])/, :vowel] # => "e"

If an invalid capture group index is given, `nil` is returned. If an invalid capture group name is given, `IndexError` is raised.

When the single String argument `substring` is given, returns the substring from `self` if found, otherwise `nil`:

    'foo'['oo'] # => "oo"
    'foo'['xx'] # => nil

`String#slice` is an alias for `String#[]`.

    static VALUE
    rb_str_aref_m(int argc, VALUE *argv, VALUE str)
    {
        if (argc == 2) {
            if (RB_TYPE_P(argv[0], T_REGEXP)) {
                return rb_str_subpat(str, argv[0], argv[1]);
            }
            else {
                long beg = NUM2LONG(argv[0]);
                long len = NUM2LONG(argv[1]);
                return rb_str_substr(str, beg, len);
            }
        }
        rb_check_arity(argc, 1, 2);
        return rb_str_aref(str, argv[0]);
    }

Also aliased as: slice
str[integer] = new_str click to toggle source
str[integer, integer] = new_str
str[range] = aString
str[regexp] = new_str
str[regexp, integer] = new_str
str[regexp, name] = new_str
str[other_str] = new_str

Element Assignment—Replaces some or all of the content of str. The portion of the string affected is determined using the same criteria as `String#[]`. If the replacement string is not the same length as the text it is replacing, the string will be adjusted accordingly. If the regular expression or string is used as the index doesn't match a position in the string, `IndexError` is raised. If the regular expression form is used, the optional second `Integer` allows you to specify which portion of the match to replace (effectively using the `MatchData` indexing rules. The forms that take an `Integer` will raise an `IndexError` if the value is out of range; the `Range` form will raise a `RangeError`, and the `Regexp` and `String` will raise an `IndexError` on negative match.

    static VALUE
    rb_str_aset_m(int argc, VALUE *argv, VALUE str)
    {
        if (argc == 3) {
            if (RB_TYPE_P(argv[0], T_REGEXP)) {
                rb_str_subpat_set(str, argv[0], argv[1], argv[2]);
            }
            else {
                rb_str_splice(str, NUM2LONG(argv[0]), NUM2LONG(argv[1]), argv[2]);
            }
            return argv[2];
        }
        rb_check_arity(argc, 2, 3);
        return rb_str_aset(str, argv[0], argv[1]);
    }

ascii_only? → true or false click to toggle source

Returns true for a string which has only ASCII characters.

    "abc".force_encoding("UTF-8").ascii_only?          #=> true
    "abc\u{6666}".force_encoding("UTF-8").ascii_only?  #=> false

    static VALUE
    rb_str_is_ascii_only_p(VALUE str)
    {
        int cr = rb_enc_str_coderange(str);

        return cr == ENC_CODERANGE_7BIT ? Qtrue : Qfalse;
    }

b → str click to toggle source

Returns a copied string whose encoding is ASCII-8BIT.

    static VALUE
    rb_str_b(VALUE str)
    {
        VALUE str2 = str_alloc(rb_cString);
        str_replace_shared_without_enc(str2, str);
        ENC_CODERANGE_CLEAR(str2);
        return str2;
    }

bytes → an_array click to toggle source

Returns an array of bytes in str. This is a shorthand for `str.each_byte.to_a`.

If a block is given, which is a deprecated form, works the same as `each_byte`.

    static VALUE
    rb_str_bytes(VALUE str)
    {
        VALUE ary = WANTARRAY("bytes", RSTRING_LEN(str));
        return rb_str_enumerate_bytes(str, ary);
    }

bytesize → integer click to toggle source

Returns the count of bytes in `self`:

    "\x80\u3042".bytesize # => 4
    "hello".bytesize # => 5

Related: `String#length`.

    static VALUE
    rb_str_bytesize(VALUE str)
    {
        return LONG2NUM(RSTRING_LEN(str));
    }

byteslice(integer) → new_str or nil click to toggle source
byteslice(integer, integer) → new_str or nil
byteslice(range) → new_str or nil

Byte Reference—If passed a single `Integer`, returns a substring of one byte at that position. If passed two `Integer` objects, returns a substring starting at the offset given by the first, and a length given by the second. If given a `Range`, a substring containing bytes at offsets given by the range is returned. In all three cases, if an offset is negative, it is counted from the end of str. Returns `nil` if the initial offset falls outside the string, the length is negative, or the beginning of the range is greater than the end. The encoding of the resulted string keeps original encoding.

    "hello".byteslice(1)     #=> "e"
    "hello".byteslice(-1)    #=> "o"
    "hello".byteslice(1, 2)  #=> "el"
    "\x80\u3042".byteslice(1, 3) #=> "\u3042"
    "\x03\u3042\xff".byteslice(1..3) #=> "\u3042"

    static VALUE
    rb_str_byteslice(int argc, VALUE *argv, VALUE str)
    {
        if (argc == 2) {
            long beg = NUM2LONG(argv[0]);
            long end = NUM2LONG(argv[1]);
            return str_byte_substr(str, beg, end, TRUE);
        }
        rb_check_arity(argc, 1, 2);
        return str_byte_aref(str, argv[0]);
    }

capitalize → new_str click to toggle source
capitalize([options]) → new_str

Returns a copy of str with the first character converted to uppercase and the remainder to lowercase.

See `String#downcase` for meaning of `options` and use with different encodings.

    "hello".capitalize    #=> "Hello"
    "HELLO".capitalize    #=> "Hello"
    "123ABC".capitalize   #=> "123abc"

    static VALUE
    rb_str_capitalize(int argc, VALUE *argv, VALUE str)
    {
        rb_encoding *enc;
        OnigCaseFoldType flags = ONIGENC_CASE_UPCASE | ONIGENC_CASE_TITLECASE;
        VALUE ret;

        flags = check_case_options(argc, argv, flags);
        enc = str_true_enc(str);
        if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return str;
        if (flags&ONIGENC_CASE_ASCII_ONLY) {
            ret = rb_str_new(0, RSTRING_LEN(str));
            rb_str_ascii_casemap(str, ret, &flags, enc);
        }
        else {
            ret = rb_str_casemap(str, &flags, enc);
        }
        return ret;
    }

capitalize! → str or nil click to toggle source
capitalize!([options]) → str or nil

Modifies str by converting the first character to uppercase and the remainder to lowercase. Returns `nil` if no changes are made. There is an exception for modern Georgian (mkhedruli/MTAVRULI), where the result is the same as for `String#downcase`, to avoid mixed case.

See `String#downcase` for meaning of `options` and use with different encodings.

    a = "hello"
    a.capitalize!   #=> "Hello"
    a               #=> "Hello"
    a.capitalize!   #=> nil

    static VALUE
    rb_str_capitalize_bang(int argc, VALUE *argv, VALUE str)
    {
        rb_encoding *enc;
        OnigCaseFoldType flags = ONIGENC_CASE_UPCASE | ONIGENC_CASE_TITLECASE;

        flags = check_case_options(argc, argv, flags);
        str_modify_keep_cr(str);
        enc = str_true_enc(str);
        if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return Qnil;
        if (flags&ONIGENC_CASE_ASCII_ONLY)
            rb_str_ascii_casemap(str, str, &flags, enc);
        else
            str_shared_replace(str, rb_str_casemap(str, &flags, enc));

        if (ONIGENC_CASE_MODIFIED&flags) return str;
        return Qnil;
    }

casecmp(other_str) → -1, 0, 1, or nil click to toggle source

Compares `self` and `other_string`, ignoring case, and returning:

- -1 if `other_string` is smaller.

- 0 if the two are equal.

- 1 if `other_string` is larger.

- `nil` if the two are incomparable.

Examples:

    'foo'.casecmp('foo') # => 0
    'foo'.casecmp('food') # => -1
    'food'.casecmp('foo') # => 1
    'FOO'.casecmp('foo') # => 0
    'foo'.casecmp('FOO') # => 0
    'foo'.casecmp(1) # => nil

    static VALUE
    rb_str_casecmp(VALUE str1, VALUE str2)
    {
        VALUE s = rb_check_string_type(str2);
        if (NIL_P(s)) {
            return Qnil;
        }
        return str_casecmp(str1, s);
    }

casecmp?(other_string) → true, false, or nil click to toggle source

Returns `true` if `self` and `other_string` are equal after Unicode case folding, otherwise `false`:

    'foo'.casecmp?('foo') # => true
    'foo'.casecmp?('food') # => false
    'food'.casecmp?('foo') # => true
    'FOO'.casecmp?('foo') # => true
    'foo'.casecmp?('FOO') # => true

Returns `nil` if the two values are incomparable:

    'foo'.casecmp?(1) # => nil

    static VALUE
    rb_str_casecmp_p(VALUE str1, VALUE str2)
    {
        VALUE s = rb_check_string_type(str2);
        if (NIL_P(s)) {
            return Qnil;
        }
        return str_casecmp_p(str1, s);
    }

center(width, padstr=' ') → new_str click to toggle source

Centers `str` in `width`. If `width` is greater than the length of `str`, returns a new `String` of length `width` with `str` centered and padded with `padstr`; otherwise, returns `str`.

    "hello".center(4)         #=> "hello"
    "hello".center(20)        #=> "       hello        "
    "hello".center(20, '123') #=> "1231231hello12312312"

    static VALUE
    rb_str_center(int argc, VALUE *argv, VALUE str)
    {
        return rb_str_justify(argc, argv, str, 'c');
    }

chars → an_array click to toggle source

Returns an array of characters in str. This is a shorthand for `str.each_char.to_a`.

If a block is given, which is a deprecated form, works the same as `each_char`.

    static VALUE
    rb_str_chars(VALUE str)
    {
        VALUE ary = WANTARRAY("chars", rb_str_strlen(str));
        return rb_str_enumerate_chars(str, ary);
    }

chomp(separator=$/) → new_str click to toggle source

Returns a new `String` with the given record separator removed from the end of str (if present). If `$/` has not been changed from the default Ruby record separator, then `chomp` also removes carriage return characters (that is it will remove `\n`, `\r`, and `\r\n`). If `$/` is an empty string, it will remove all trailing newlines from the string.

    "hello".chomp                #=> "hello"
    "hello\n".chomp              #=> "hello"
    "hello\r\n".chomp            #=> "hello"
    "hello\n\r".chomp            #=> "hello\n"
    "hello\r".chomp              #=> "hello"
    "hello \n there".chomp       #=> "hello \n there"
    "hello".chomp("llo")         #=> "he"
    "hello\r\n\r\n".chomp('')    #=> "hello"
    "hello\r\n\r\r\n".chomp('')  #=> "hello\r\n\r"

    static VALUE
    rb_str_chomp(int argc, VALUE *argv, VALUE str)
    {
        VALUE rs = chomp_rs(argc, argv);
        if (NIL_P(rs)) return str_duplicate(rb_cString, str);
        return rb_str_subseq(str, 0, chompped_length(str, rs));
    }

chomp!(separator=$/) → str or nil click to toggle source

Modifies str in place as described for `String#chomp`, returning str, or `nil` if no modifications were made.

    static VALUE
    rb_str_chomp_bang(int argc, VALUE *argv, VALUE str)
    {
        VALUE rs;
        str_modifiable(str);
        if (RSTRING_LEN(str) == 0) return Qnil;
        rs = chomp_rs(argc, argv);
        if (NIL_P(rs)) return Qnil;
        return rb_str_chomp_string(str, rs);
    }

chop → new_str click to toggle source

Returns a new `String` with the last character removed. If the string ends with `\r\n`, both characters are removed. Applying `chop` to an empty string returns an empty string. `String#chomp` is often a safer alternative, as it leaves the string unchanged if it doesn't end in a record separator.

    "string\r\n".chop   #=> "string"
    "string\n\r".chop   #=> "string\n"
    "string\n".chop     #=> "string"
    "string".chop       #=> "strin"
    "x".chop.chop       #=> ""

    static VALUE
    rb_str_chop(VALUE str)
    {
        return rb_str_subseq(str, 0, chopped_length(str));
    }

chop! → str or nil click to toggle source

Processes str as for `String#chop`, returning str, or `nil` if str is the empty string. See also `String#chomp!`.

    static VALUE
    rb_str_chop_bang(VALUE str)
    {
        str_modify_keep_cr(str);
        if (RSTRING_LEN(str) > 0) {
            long len;
            len = chopped_length(str);
            STR_SET_LEN(str, len);
            TERM_FILL(&RSTRING_PTR(str)[len], TERM_LEN(str));
            if (ENC_CODERANGE(str) != ENC_CODERANGE_7BIT) {
                ENC_CODERANGE_CLEAR(str);
            }
            return str;
        }
        return Qnil;
    }

chr → string click to toggle source

Returns a one-character string at the beginning of the string.

    a = "abcde"
    a.chr    #=> "a"

    static VALUE
    rb_str_chr(VALUE str)
    {
        return rb_str_substr(str, 0, 1);
    }

clear → string click to toggle source

Makes string empty.

    a = "abcde"
    a.clear    #=> ""

    static VALUE
    rb_str_clear(VALUE str)
    {
        str_discard(str);
        STR_SET_EMBED(str);
        STR_SET_EMBED_LEN(str, 0);
        RSTRING_PTR(str)[0] = 0;
        if (rb_enc_asciicompat(STR_ENC_GET(str)))
            ENC_CODERANGE_SET(str, ENC_CODERANGE_7BIT);
        else
            ENC_CODERANGE_SET(str, ENC_CODERANGE_VALID);
        return str;
    }

codepoints → an_array click to toggle source

Returns an array of the `Integer` ordinals of the characters in str. This is a shorthand for `str.each_codepoint.to_a`.

If a block is given, which is a deprecated form, works the same as `each_codepoint`.

    static VALUE
    rb_str_codepoints(VALUE str)
    {
        VALUE ary = WANTARRAY("codepoints", rb_str_strlen(str));
        return rb_str_enumerate_codepoints(str, ary);
    }

concat(*objects) → new_string click to toggle source

Returns a new String containing the concatenation of `self` and all objects in `objects`:

    s = 'foo'
    s.concat('bar', 'baz') # => "foobarbaz"

For each given object `object` that is an Integer, the value is considered a codepoint and converted to a character before concatenation:

    s = 'foo'
    s.concat(32, 'bar', 32, 'baz') # => "foo bar baz"

Related: `String#<<`, which takes a single argument.

    static VALUE
    rb_str_concat_multi(int argc, VALUE *argv, VALUE str)
    {
        str_modifiable(str);

        if (argc == 1) {
            return rb_str_concat(str, argv[0]);
        }
        else if (argc > 1) {
            int i;
            VALUE arg_str = rb_str_tmp_new(0);
            rb_enc_copy(arg_str, str);
            for (i = 0; i < argc; i++) {
                rb_str_concat(arg_str, argv[i]);
            }
            rb_str_buf_append(str, arg_str);
        }

        return str;
    }

count([other_str]+) → integer click to toggle source

Each `other_str` parameter defines a set of characters to count. The intersection of these sets defines the characters to count in `str`. Any `other_str` that starts with a caret `^` is negated. The sequence `c1-c2` means all characters between c1 and c2. The backslash character `\` can be used to escape `^` or `-` and is otherwise ignored unless it appears at the end of a sequence or the end of a `other_str`.

    a = "hello world"
    a.count "lo"                   #=> 5
    a.count "lo", "o"              #=> 2
    a.count "hello", "^l"          #=> 4
    a.count "ej-m"                 #=> 4

    "hello^world".count "\\^aeiou" #=> 4
    "hello-world".count "a\\-eo"   #=> 4

    c = "hello world\\r\\n"
    c.count "\\"                   #=> 2
    c.count "\\A"                  #=> 0
    c.count "X-\\w"                #=> 3

    static VALUE
    rb_str_count(int argc, VALUE *argv, VALUE str)
    {
        char table[TR_TABLE_SIZE];
        rb_encoding *enc = 0;
        VALUE del = 0, nodel = 0, tstr;
        char *s, *send;
        int i;
        int ascompat;

        rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);

        tstr = argv[0];
        StringValue(tstr);
        enc = rb_enc_check(str, tstr);
        if (argc == 1) {
            const char *ptstr;
            if (RSTRING_LEN(tstr) == 1 && rb_enc_asciicompat(enc) &&
                (ptstr = RSTRING_PTR(tstr),
                 ONIGENC_IS_ALLOWED_REVERSE_MATCH(enc, (const unsigned char *)ptstr, (const unsigned char *)ptstr+1)) &&
                !is_broken_string(str)) {
                int n = 0;
                int clen;
                unsigned char c = rb_enc_codepoint_len(ptstr, ptstr+1, &clen, enc);

                s = RSTRING_PTR(str);
                if (!s || RSTRING_LEN(str) == 0) return INT2FIX(0);
                send = RSTRING_END(str);
                while (s < send) {
                    if (*(unsigned char*)s++ == c) n++;
                }
                return INT2NUM(n);
            }
        }

        tr_setup_table(tstr, table, TRUE, &del, &nodel, enc);
        for (i=1; i<argc; i++) {
            tstr = argv[i];
            StringValue(tstr);
            enc = rb_enc_check(str, tstr);
            tr_setup_table(tstr, table, FALSE, &del, &nodel, enc);
        }

        s = RSTRING_PTR(str);
        if (!s || RSTRING_LEN(str) == 0) return INT2FIX(0);
        send = RSTRING_END(str);
        ascompat = rb_enc_asciicompat(enc);
        i = 0;
        while (s < send) {
            unsigned int c;

            if (ascompat && (c = *(unsigned char*)s) < 0x80) {
                if (table[c]) {
                    i++;
                }
                s++;
            }
            else {
                int clen;
                c = rb_enc_codepoint_len(s, send, &clen, enc);
                if (tr_find(c, table, del, nodel)) {
                    i++;
                }
                s += clen;
            }
        }

        return INT2NUM(i);
    }

crypt(salt_str) → new_str click to toggle source

Returns the string generated by calling `crypt(3)` standard library function with `str` and `salt_str`, in this order, as its arguments. Please do not use this method any longer. It is legacy; provided only for backward compatibility with ruby scripts in earlier days. It is bad to use in contemporary programs for several reasons:

- Behaviour of C's `crypt(3)` depends on the OS it is run. The generated string lacks data portability.

- On some OSes such as Mac OS, `crypt(3)` never fails (i.e. silently ends up in unexpected results).

- On some OSes such as Mac OS, `crypt(3)` is not thread safe.

- So-called “traditional” usage of `crypt(3)` is very very very weak. According to its manpage, Linux's traditional `crypt(3)` output has only 2**56 variations; too easy to brute force today. And this is the default behaviour.

- In order to make things robust some OSes implement so-called “modular” usage. To go through, you have to do a complex build-up of the `salt_str` parameter, by hand. Failure in generation of a proper salt string tends not to yield any errors; typos in parameters are normally not detectable.

  - For instance, in the following example, the second invocation of `String#crypt` is wrong; it has a typo in “round=” (lacks “s”). However the call does not fail and something unexpected is generated.

        "foo".crypt("$5$rounds=1000$salt$") # OK, proper usage
        "foo".crypt("$5$round=1000$salt$")  # Typo not detected

- Even in the “modular” mode, some hash functions are considered archaic and no longer recommended at all; for instance module `$1$` is officially abandoned by its author: see phk.freebsd.dk/sagas/md5crypt_eol.html . For another instance module `$3$` is considered completely broken: see the manpage of FreeBSD.

- On some OS such as Mac OS, there is no modular mode. Yet, as written above, `crypt(3)` on Mac OS never fails. This means even if you build up a proper salt string it generates a traditional DES hash anyways, and there is no way for you to be aware of.

      "foo".crypt("$5$rounds=1000$salt$") # => "$5fNPQMxC5j6."

If for some reason you cannot migrate to other secure contemporary password hashing algorithms, install the string-crypt gem and `require 'string/crypt'` to continue using it.

    static VALUE
    rb_str_crypt(VALUE str, VALUE salt)
    {
    #ifdef HAVE_CRYPT_R
        VALUE databuf;
        struct crypt_data *data;
    #   define CRYPT_END() ALLOCV_END(databuf)
    #else
        extern char *crypt(const char *, const char *);
    #   define CRYPT_END() (void)0
    #endif
        VALUE result;
        const char *s, *saltp;
        char *res;
    #ifdef BROKEN_CRYPT
        char salt_8bit_clean[3];
    #endif

        StringValue(salt);
        mustnot_wchar(str);
        mustnot_wchar(salt);
        if (RSTRING_LEN(salt) < 2) {
            goto short_salt;
        }

        s = StringValueCStr(str);
        saltp = RSTRING_PTR(salt);
        if (!saltp[0] || !saltp[1]) goto short_salt;
    #ifdef BROKEN_CRYPT
        if (!ISASCII((unsigned char)saltp[0]) || !ISASCII((unsigned char)saltp[1])) {
            salt_8bit_clean[0] = saltp[0] & 0x7f;
            salt_8bit_clean[1] = saltp[1] & 0x7f;
            salt_8bit_clean[2] = '\0';
            saltp = salt_8bit_clean;
        }
    #endif
    #ifdef HAVE_CRYPT_R
        data = ALLOCV(databuf, sizeof(struct crypt_data));
    # ifdef HAVE_STRUCT_CRYPT_DATA_INITIALIZED
        data->initialized = 0;
    # endif
        res = crypt_r(s, saltp, data);
    #else
        res = crypt(s, saltp);
    #endif
        if (!res) {
            int err = errno;
            CRYPT_END();
            rb_syserr_fail(err, "crypt");
        }
        result = rb_str_new_cstr(res);
        CRYPT_END();
        return result;

      short_salt:
        rb_raise(rb_eArgError, "salt too short (need >=2 bytes)");
        UNREACHABLE_RETURN(Qundef);
    }

delete([other_str]+) → new_str click to toggle source

Returns a copy of str with all characters in the intersection of its arguments deleted. Uses the same rules for building the set of characters as `String#count`.

    "hello".delete "l","lo"        #=> "heo"
    "hello".delete "lo"            #=> "he"
    "hello".delete "aeiou", "^e"   #=> "hell"
    "hello".delete "ej-m"          #=> "ho"

    static VALUE
    rb_str_delete(int argc, VALUE *argv, VALUE str)
    {
        str = str_duplicate(rb_cString, str);
        rb_str_delete_bang(argc, argv, str);
        return str;
    }

delete!([other_str]+) → str or nil click to toggle source

Performs a `delete` operation in place, returning str, or `nil` if str was not modified.

    static VALUE
    rb_str_delete_bang(int argc, VALUE *argv, VALUE str)
    {
        char squeez[TR_TABLE_SIZE];
        rb_encoding *enc = 0;
        char *s, *send, *t;
        VALUE del = 0, nodel = 0;
        int modify = 0;
        int i, ascompat, cr;

        if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return Qnil;
        rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
        for (i=0; i<argc; i++) {
            VALUE s = argv[i];

            StringValue(s);
            enc = rb_enc_check(str, s);
            tr_setup_table(s, squeez, i==0, &del, &nodel, enc);
        }

        str_modify_keep_cr(str);
        ascompat = rb_enc_asciicompat(enc);
        s = t = RSTRING_PTR(str);
        send = RSTRING_END(str);
        cr = ascompat ? ENC_CODERANGE_7BIT : ENC_CODERANGE_VALID;
        while (s < send) {
            unsigned int c;
            int clen;

            if (ascompat && (c = *(unsigned char*)s) < 0x80) {
                if (squeez[c]) {
                    modify = 1;
                }
                else {
                    if (t != s) *t = c;
                    t++;
                }
                s++;
            }
            else {
                c = rb_enc_codepoint_len(s, send, &clen, enc);

                if (tr_find(c, squeez, del, nodel)) {
                    modify = 1;
                }
                else {
                    if (t != s) rb_enc_mbcput(c, t, enc);
                    t += clen;
                    if (cr == ENC_CODERANGE_7BIT) cr = ENC_CODERANGE_VALID;
                }
                s += clen;
            }
        }
        TERM_FILL(t, TERM_LEN(str));
        STR_SET_LEN(str, t - RSTRING_PTR(str));
        ENC_CODERANGE_SET(str, cr);

        if (modify) return str;
        return Qnil;
    }

delete_prefix(prefix) → new_str click to toggle source

Returns a copy of str with leading `prefix` deleted.

    "hello".delete_prefix("hel") #=> "lo"
    "hello".delete_prefix("llo") #=> "hello"

    static VALUE
    rb_str_delete_prefix(VALUE str, VALUE prefix)
    {
        long prefixlen;

        prefixlen = deleted_prefix_length(str, prefix);
        if (prefixlen <= 0) return str_duplicate(rb_cString, str);

        return rb_str_subseq(str, prefixlen, RSTRING_LEN(str) - prefixlen);
    }

delete_prefix!(prefix) → self or nil click to toggle source

Deletes leading `prefix` from str, returning `nil` if no change was made.

    "hello".delete_prefix!("hel") #=> "lo"
    "hello".delete_prefix!("llo") #=> nil

    static VALUE
    rb_str_delete_prefix_bang(VALUE str, VALUE prefix)
    {
        long prefixlen;
        str_modify_keep_cr(str);

        prefixlen = deleted_prefix_length(str, prefix);
        if (prefixlen <= 0) return Qnil;

        return rb_str_drop_bytes(str, prefixlen);
    }

delete_suffix(suffix) → new_str click to toggle source

Returns a copy of str with trailing `suffix` deleted.

    "hello".delete_suffix("llo") #=> "he"
    "hello".delete_suffix("hel") #=> "hello"

    static VALUE
    rb_str_delete_suffix(VALUE str, VALUE suffix)
    {
        long suffixlen;

        suffixlen = deleted_suffix_length(str, suffix);
        if (suffixlen <= 0) return str_duplicate(rb_cString, str);

        return rb_str_subseq(str, 0, RSTRING_LEN(str) - suffixlen);
    }

delete_suffix!(suffix) → self or nil click to toggle source

Deletes trailing `suffix` from str, returning `nil` if no change was made.

    "hello".delete_suffix!("llo") #=> "he"
    "hello".delete_suffix!("hel") #=> nil

    static VALUE
    rb_str_delete_suffix_bang(VALUE str, VALUE suffix)
    {
        long olen, suffixlen, len;
        str_modifiable(str);

        suffixlen = deleted_suffix_length(str, suffix);
        if (suffixlen <= 0) return Qnil;

        olen = RSTRING_LEN(str);
        str_modify_keep_cr(str);
        len = olen - suffixlen;
        STR_SET_LEN(str, len);
        TERM_FILL(&RSTRING_PTR(str)[len], TERM_LEN(str));
        if (ENC_CODERANGE(str) != ENC_CODERANGE_7BIT) {
            ENC_CODERANGE_CLEAR(str);
        }
        return str;
    }

downcase → new_str click to toggle source
downcase([options]) → new_str

Returns a copy of str with all uppercase letters replaced with their lowercase counterparts. Which letters exactly are replaced, and by which other letters, depends on the presence or absence of options, and on the `encoding` of the string.

The meaning of the `options` is as follows:

No option

  Full Unicode case mapping, suitable for most languages (see :turkic and :lithuanian options below for exceptions). Context-dependent case mapping as described in Table 3-14 of the Unicode standard is currently not supported.

:ascii

  Only the ASCII region, i.e. the characters “A'' to “Z'' and “a'' to “z'', are affected. This option cannot be combined with any other option.

:turkic

  Full Unicode case mapping, adapted for Turkic languages (Turkish, Azerbaijani, …). This means that upper case I is mapped to lower case dotless i, and so on.

:lithuanian

  Currently, just full Unicode case mapping. In the future, full Unicode case mapping adapted for Lithuanian (keeping the dot on the lower case i even if there is an accent on top).

:fold

  Only available on `downcase` and `downcase!`. Unicode case folding, which is more far-reaching than Unicode case mapping. This option currently cannot be combined with any other option (i.e. there is currently no variant for turkic languages).

Please note that several assumptions that are valid for ASCII-only case conversions do not hold for more general case conversions. For example, the length of the result may not be the same as the length of the input (neither in characters nor in bytes), some roundtrip assumptions (e.g. str.downcase == str.upcase.downcase) may not apply, and Unicode normalization (i.e. `String#unicode_normalize`) is not necessarily maintained by case mapping operations.

Non-ASCII case mapping/folding is currently supported for UTF-8, UTF-16BE/LE, UTF-32BE/LE, and ISO-8859-1~16 Strings/Symbols. This support will be extended to other encodings.

    "hEllO".downcase   #=> "hello"

    static VALUE
    rb_str_downcase(int argc, VALUE *argv, VALUE str)
    {
        rb_encoding *enc;
        OnigCaseFoldType flags = ONIGENC_CASE_DOWNCASE;
        VALUE ret;

        flags = check_case_options(argc, argv, flags);
        enc = str_true_enc(str);
        if (case_option_single_p(flags, enc, str)) {
            ret = rb_str_new(RSTRING_PTR(str), RSTRING_LEN(str));
            str_enc_copy(ret, str);
            downcase_single(ret);
        }
        else if (flags&ONIGENC_CASE_ASCII_ONLY) {
            ret = rb_str_new(0, RSTRING_LEN(str));
            rb_str_ascii_casemap(str, ret, &flags, enc);
        }
        else {
            ret = rb_str_casemap(str, &flags, enc);
        }

        return ret;
    }

downcase! → str or nil click to toggle source
downcase!([options]) → str or nil

Downcases the contents of str, returning `nil` if no changes were made.

See `String#downcase` for meaning of `options` and use with different encodings.

    static VALUE
    rb_str_downcase_bang(int argc, VALUE *argv, VALUE str)
    {
        rb_encoding *enc;
        OnigCaseFoldType flags = ONIGENC_CASE_DOWNCASE;

        flags = check_case_options(argc, argv, flags);
        str_modify_keep_cr(str);
        enc = str_true_enc(str);
        if (case_option_single_p(flags, enc, str)) {
            if (downcase_single(str))
                flags |= ONIGENC_CASE_MODIFIED;
        }
        else if (flags&ONIGENC_CASE_ASCII_ONLY)
            rb_str_ascii_casemap(str, str, &flags, enc);
        else
            str_shared_replace(str, rb_str_casemap(str, &flags, enc));

        if (ONIGENC_CASE_MODIFIED&flags) return str;
        return Qnil;
    }

dump → new_str click to toggle source

Returns a quoted version of the string with all non-printing characters replaced by `\xHH` notation and all special characters escaped.

This method can be used for round-trip: if the resulting `new_str` is eval'ed, it will produce the original string.

    "hello \n ''".dump     #=> "\"hello \\n ''\""
    "\f\x00\xff\\\"".dump  #=> "\"\\f\\x00\\xFF\\\\\\\"\""

See also `String#undump`.

    VALUE
    rb_str_dump(VALUE str)
    {
        int encidx = rb_enc_get_index(str);
        rb_encoding *enc = rb_enc_from_index(encidx);
        long len;
        const char *p, *pend;
        char *q, *qend;
        VALUE result;
        int u8 = (encidx == rb_utf8_encindex());
        static const char nonascii_suffix[] = ".dup.force_encoding(\"%s\")";

        len = 2;                    /* "" */
        if (!rb_enc_asciicompat(enc)) {
            len += strlen(nonascii_suffix) - rb_strlen_lit("%s");
            len += strlen(enc->name);
        }

        p = RSTRING_PTR(str); pend = p + RSTRING_LEN(str);
        while (p < pend) {
            int clen;
            unsigned char c = *p++;

            switch (c) {
              case '"':  case '\\':
              case '\n': case '\r':
              case '\t': case '\f':
              case '\013': case '\010': case '\007': case '\033':
                clen = 2;
                break;

              case '#':
                clen = IS_EVSTR(p, pend) ? 2 : 1;
                break;

              default:
                if (ISPRINT(c)) {
                    clen = 1;
                }
                else {
                    if (u8 && c > 0x7F) { /* \u notation */
                        int n = rb_enc_precise_mbclen(p-1, pend, enc);
                        if (MBCLEN_CHARFOUND_P(n)) {
                            unsigned int cc = rb_enc_mbc_to_codepoint(p-1, pend, enc);
                            if (cc <= 0xFFFF)
                                clen = 6;  /* \uXXXX */
                            else if (cc <= 0xFFFFF)
                                clen = 9;  /* \u{XXXXX} */
                            else
                                clen = 10; /* \u{XXXXXX} */
                            p += MBCLEN_CHARFOUND_LEN(n)-1;
                            break;
                        }
                    }
                    clen = 4;     /* \xNN */
                }
                break;
            }

            if (clen > LONG_MAX - len) {
                rb_raise(rb_eRuntimeError, "string size too big");
            }
            len += clen;
        }

        result = rb_str_new(0, len);
        p = RSTRING_PTR(str); pend = p + RSTRING_LEN(str);
        q = RSTRING_PTR(result); qend = q + len + 1;

        *q++ = '"';
        while (p < pend) {
            unsigned char c = *p++;

            if (c == '"' || c == '\\') {
                *q++ = '\\';
                *q++ = c;
            }
            else if (c == '#') {
                if (IS_EVSTR(p, pend)) *q++ = '\\';
                *q++ = '#';
            }
            else if (c == '\n') {
                *q++ = '\\';
                *q++ = 'n';
            }
            else if (c == '\r') {
                *q++ = '\\';
                *q++ = 'r';
            }
            else if (c == '\t') {
                *q++ = '\\';
                *q++ = 't';
            }
            else if (c == '\f') {
                *q++ = '\\';
                *q++ = 'f';
            }
            else if (c == '\013') {
                *q++ = '\\';
                *q++ = 'v';
            }
            else if (c == '\010') {
                *q++ = '\\';
                *q++ = 'b';
            }
            else if (c == '\007') {
                *q++ = '\\';
                *q++ = 'a';
            }
            else if (c == '\033') {
                *q++ = '\\';
                *q++ = 'e';
            }
            else if (ISPRINT(c)) {
                *q++ = c;
            }
            else {
                *q++ = '\\';
                if (u8) {
                    int n = rb_enc_precise_mbclen(p-1, pend, enc) - 1;
                    if (MBCLEN_CHARFOUND_P(n)) {
                        int cc = rb_enc_mbc_to_codepoint(p-1, pend, enc);
                        p += n;
                        if (cc <= 0xFFFF)
                            snprintf(q, qend-q, "u%04X", cc);    /* \uXXXX */
                        else
                            snprintf(q, qend-q, "u{%X}", cc);  /* \u{XXXXX} or \u{XXXXXX} */
                        q += strlen(q);
                        continue;
                    }
                }
                snprintf(q, qend-q, "x%02X", c);
                q += 3;
            }
        }
        *q++ = '"';
        *q = '\0';
        if (!rb_enc_asciicompat(enc)) {
            snprintf(q, qend-q, nonascii_suffix, enc->name);
            encidx = rb_ascii8bit_encindex();
        }
        /* result from dump is ASCII */
        rb_enc_associate_index(result, encidx);
        ENC_CODERANGE_SET(result, ENC_CODERANGE_7BIT);
        return result;
    }

each_byte {|integer| block } → str click to toggle source
each_byte → an_enumerator

Passes each byte in str to the given block, or returns an enumerator if no block is given.

    "hello".each_byte {|c| print c, ' ' }

produces:

    104 101 108 108 111

    static VALUE
    rb_str_each_byte(VALUE str)
    {
        RETURN_SIZED_ENUMERATOR(str, 0, 0, rb_str_each_byte_size);
        return rb_str_enumerate_bytes(str, 0);
    }

each_char {|cstr| block } → str click to toggle source
each_char → an_enumerator

Passes each character in str to the given block, or returns an enumerator if no block is given.

    "hello".each_char {|c| print c, ' ' }

produces:

    h e l l o

    static VALUE
    rb_str_each_char(VALUE str)
    {
        RETURN_SIZED_ENUMERATOR(str, 0, 0, rb_str_each_char_size);
        return rb_str_enumerate_chars(str, 0);
    }

each_codepoint {|integer| block } → str click to toggle source
each_codepoint → an_enumerator

Passes the `Integer` ordinal of each character in str, also known as a codepoint when applied to Unicode strings to the given block. For encodings other than UTF-8/UTF-16(BE|LE)/UTF-32(BE|LE), values are directly derived from the binary representation of each character.

If no block is given, an enumerator is returned instead.

    "hello\u0639".each_codepoint {|c| print c, ' ' }

produces:

    104 101 108 108 111 1593

    static VALUE
    rb_str_each_codepoint(VALUE str)
    {
        RETURN_SIZED_ENUMERATOR(str, 0, 0, rb_str_each_char_size);
        return rb_str_enumerate_codepoints(str, 0);
    }

each_grapheme_cluster {|cstr| block } → str click to toggle source
each_grapheme_cluster → an_enumerator

Passes each grapheme cluster in str to the given block, or returns an enumerator if no block is given. Unlike `String#each_char`, this enumerates by grapheme clusters defined by Unicode Standard Annex #29 unicode.org/reports/tr29/

    "a\u0300".each_char.to_a.size #=> 2
    "a\u0300".each_grapheme_cluster.to_a.size #=> 1

    static VALUE
    rb_str_each_grapheme_cluster(VALUE str)
    {
        RETURN_SIZED_ENUMERATOR(str, 0, 0, rb_str_each_grapheme_cluster_size);
        return rb_str_enumerate_grapheme_clusters(str, 0);
    }

each_line(separator=$/, chomp: false) {|substr| block } → str click to toggle source
each_line(separator=$/, chomp: false) → an_enumerator

Splits str using the supplied parameter as the record separator (`$/` by default), passing each substring in turn to the supplied block. If a zero-length record separator is supplied, the string is split into paragraphs delimited by multiple successive newlines.

If `chomp` is `true`, `separator` will be removed from the end of each line.

If no block is given, an enumerator is returned instead.

    "hello\nworld".each_line {|s| p s}
    # prints:
    #   "hello\n"
    #   "world"

    "hello\nworld".each_line('l') {|s| p s}
    # prints:
    #   "hel"
    #   "l"
    #   "o\nworl"
    #   "d"

    "hello\n\n\nworld".each_line('') {|s| p s}
    # prints
    #   "hello\n\n"
    #   "world"

    "hello\nworld".each_line(chomp: true) {|s| p s}
    # prints:
    #   "hello"
    #   "world"

    "hello\nworld".each_line('l', chomp: true) {|s| p s}
    # prints:
    #   "he"
    #   ""
    #   "o\nwor"
    #   "d"

    static VALUE
    rb_str_each_line(int argc, VALUE *argv, VALUE str)
    {
        RETURN_SIZED_ENUMERATOR(str, argc, argv, 0);
        return rb_str_enumerate_lines(argc, argv, str, 0);
    }

empty? → true or false click to toggle source

Returns `true` if the length of `self` is zero, `false` otherwise:

    "hello".empty? # => false
    " ".empty? # => false
    "".empty? # => true

    static VALUE
    rb_str_empty(VALUE str)
    {
        if (RSTRING_LEN(str) == 0)
            return Qtrue;
        return Qfalse;
    }

encode(encoding, **options) → str click to toggle source
encode(dst_encoding, src_encoding, **options) → str
encode(**options) → str

The first form returns a copy of `str` transcoded to encoding `encoding`. The second form returns a copy of `str` transcoded from src_encoding to dst_encoding. The last form returns a copy of `str` transcoded to `Encoding.default_internal`.

By default, the first and second form raise `Encoding::UndefinedConversionError` for characters that are undefined in the destination encoding, and `Encoding::InvalidByteSequenceError` for invalid byte sequences in the source encoding. The last form by default does not raise exceptions but uses replacement strings.

The `options` keyword arguments give details for conversion. The arguments are:

:invalid

  If the value is `:replace`, `encode` replaces invalid byte sequences in `str` with the replacement character. The default is to raise the `Encoding::InvalidByteSequenceError` exception

:undef

  If the value is `:replace`, `encode` replaces characters which are undefined in the destination encoding with the replacement character. The default is to raise the `Encoding::UndefinedConversionError`.

:replace

  Sets the replacement string to the given value. The default replacement string is “uFFFD” for Unicode encoding forms, and “?” otherwise.

:fallback

  Sets the replacement string by the given object for undefined character. The object should be a `Hash`, a `Proc`, a `Method`, or an object which has [] method. Its key is an undefined character encoded in the source encoding of current transcoder. Its value can be any encoding until it can be converted into the destination encoding of the transcoder.

:xml

  The value must be `:text` or `:attr`. If the value is `:text` `encode` replaces undefined characters with their (upper-case hexadecimal) numeric character references. '&', '<', and '>' are converted to “&amp;”, “&lt;”, and “&gt;”, respectively. If the value is `:attr`, `encode` also quotes the replacement result (using '“'), and replaces '”' with “&quot;”.

:cr_newline

  Replaces LF (“n”) with CR (“r”) if value is true.

:crlf_newline

  Replaces LF (“n”) with CRLF (“rn”) if value is true.

:universal_newline

  Replaces CRLF (“rn”) and CR (“r”) with LF (“n”) if value is true.

    static VALUE
    str_encode(int argc, VALUE *argv, VALUE str)
    {
        VALUE newstr = str;
        int encidx = str_transcode(argc, argv, &newstr);
        return encoded_dup(newstr, str, encidx);
    }

encode!(encoding, **options) → str click to toggle source
encode!(dst_encoding, src_encoding, **options) → str

The first form transcodes the contents of str from str.encoding to `encoding`. The second form transcodes the contents of str from src_encoding to dst_encoding. The `options` keyword arguments give details for conversion. See `String#encode` for details. Returns the string even if no changes were made.

    static VALUE
    str_encode_bang(int argc, VALUE *argv, VALUE str)
    {
        VALUE newstr;
        int encidx;

        rb_check_frozen(str);

        newstr = str;
        encidx = str_transcode(argc, argv, &newstr);

        if (encidx < 0) return str;
        if (newstr == str) {
            rb_enc_associate_index(str, encidx);
            return str;
        }
        rb_str_shared_replace(str, newstr);
        return str_encode_associate(str, encidx);
    }

encoding → encoding click to toggle source

Returns the `Encoding` object that represents the encoding of obj.

    VALUE
    rb_obj_encoding(VALUE obj)
    {
        int idx = rb_enc_get_index(obj);
        if (idx < 0) {
    	rb_raise(rb_eTypeError, "unknown encoding");
        }
        return rb_enc_from_encoding_index(idx & ENC_INDEX_MASK);
    }

end_with?([suffixes]+) → true or false click to toggle source

Returns true if `str` ends with one of the `suffixes` given.

    "hello".end_with?("ello")               #=> true

    # returns true if one of the +suffixes+ matches.
    "hello".end_with?("heaven", "ello")     #=> true
    "hello".end_with?("heaven", "paradise") #=> false

    static VALUE
    rb_str_end_with(int argc, VALUE *argv, VALUE str)
    {
        int i;
        char *p, *s, *e;
        rb_encoding *enc;

        for (i=0; i<argc; i++) {
            VALUE tmp = argv[i];
            StringValue(tmp);
            enc = rb_enc_check(str, tmp);
            if (RSTRING_LEN(str) < RSTRING_LEN(tmp)) continue;
            p = RSTRING_PTR(str);
            e = p + RSTRING_LEN(str);
            s = e - RSTRING_LEN(tmp);
            if (rb_enc_left_char_head(p, s, e, enc) != s)
                continue;
            if (memcmp(s, RSTRING_PTR(tmp), RSTRING_LEN(tmp)) == 0)
                return Qtrue;
        }
        return Qfalse;
    }

eql?(object) → true or false click to toggle source

Returns `true` if `object` has the same length and content; as `self`; `false` otherwise:

    s = 'foo'
    s.eql?('foo') # => true
    s.eql?('food') # => false
    s.eql?('FOO') # => false

Returns `false` if the two strings' encodings are not compatible:

    "\u{e4 f6 fc}".encode("ISO-8859-1").eql?("\u{c4 d6 dc}") # => false

    MJIT_FUNC_EXPORTED VALUE
    rb_str_eql(VALUE str1, VALUE str2)
    {
        if (str1 == str2) return Qtrue;
        if (!RB_TYPE_P(str2, T_STRING)) return Qfalse;
        return rb_str_eql_internal(str1, str2);
    }

force_encoding(encoding) → str click to toggle source

Changes the encoding to `encoding` and returns self.

    static VALUE
    rb_str_force_encoding(VALUE str, VALUE enc)
    {
        str_modifiable(str);
        rb_enc_associate(str, rb_to_encoding(enc));
        ENC_CODERANGE_CLEAR(str);
        return str;
    }

freeze() click to toggle source

    VALUE
    rb_str_freeze(VALUE str)
    {
        if (OBJ_FROZEN(str)) return str;
        rb_str_resize(str, RSTRING_LEN(str));
        return rb_obj_freeze(str);
    }

getbyte(index) → 0 .. 255 click to toggle source

returns the indexth byte as an integer.

    static VALUE
    rb_str_getbyte(VALUE str, VALUE index)
    {
        long pos = NUM2LONG(index);

        if (pos < 0)
            pos += RSTRING_LEN(str);
        if (pos < 0 ||  RSTRING_LEN(str) <= pos)
            return Qnil;

        return INT2FIX((unsigned char)RSTRING_PTR(str)[pos]);
    }

grapheme_clusters → an_array click to toggle source

Returns an array of grapheme clusters in str. This is a shorthand for `str.each_grapheme_cluster.to_a`.

If a block is given, which is a deprecated form, works the same as `each_grapheme_cluster`.

    static VALUE
    rb_str_grapheme_clusters(VALUE str)
    {
        VALUE ary = WANTARRAY("grapheme_clusters", rb_str_strlen(str));
        return rb_str_enumerate_grapheme_clusters(str, ary);
    }

gsub(pattern, replacement) → new_str click to toggle source
gsub(pattern, hash) → new_str
gsub(pattern) {|match| block } → new_str
gsub(pattern) → enumerator

Returns a copy of str with all occurrences of pattern substituted for the second argument. The pattern is typically a `Regexp`; if given as a `String`, any regular expression metacharacters it contains will be interpreted literally, e.g. `\d` will match a backslash followed by 'd', instead of a digit.

If `replacement` is a `String` it will be substituted for the matched text. It may contain back-references to the pattern's capture groups of the form `\d`, where d is a group number, or `\k<n>`, where n is a group name. Similarly, `\&`, `\'`, `\``, and `+` correspond to special variables, `$&`, `$'`, `$``, and `$+`, respectively. (See regexp.rdoc for details.) `\0` is the same as `\&`. `\\` is interpreted as an escape, i.e., a single backslash. Note that, within `replacement` the special match variables, such as `$&`, will not refer to the current match.

If the second argument is a `Hash`, and the matched text is one of its keys, the corresponding value is the replacement string.

In the block form, the current match string is passed in as a parameter, and variables such as `$1`, `$2`, `$``, `$&`, and `$'` will be set appropriately. (See regexp.rdoc for details.) The value returned by the block will be substituted for the match on each call.

When neither a block nor a second argument is supplied, an `Enumerator` is returned.

    "hello".gsub(/[aeiou]/, '*')                  #=> "h*ll*"
    "hello".gsub(/([aeiou])/, '<\1>')             #=> "h<e>ll<o>"
    "hello".gsub(/./) {|s| s.ord.to_s + ' '}      #=> "104 101 108 108 111 "
    "hello".gsub(/(?<foo>[aeiou])/, '{\k<foo>}')  #=> "h{e}ll{o}"
    'hello'.gsub(/[eo]/, 'e' => 3, 'o' => '*')    #=> "h3ll*"

Note that a string literal consumes backslashes. (See syntax/literals.rdoc for details on string literals.) Back-references are typically preceded by an additional backslash. For example, if you want to write a back-reference `\&` in `replacement` with a double-quoted string literal, you need to write: `"..\\&.."`. If you want to write a non-back-reference string `\&` in `replacement`, you need first to escape the backslash to prevent this method from interpreting it as a back-reference, and then you need to escape the backslashes again to prevent a string literal from consuming them: `"..\\\\&.."`. You may want to use the block form to avoid a lot of backslashes.

    static VALUE
    rb_str_gsub(int argc, VALUE *argv, VALUE str)
    {
        return str_gsub(argc, argv, str, 0);
    }

gsub!(pattern, replacement) → str or nil click to toggle source
gsub!(pattern, hash) → str or nil
gsub!(pattern) {|match| block } → str or nil
gsub!(pattern) → an_enumerator

Performs the substitutions of `String#gsub` in place, returning str, or `nil` if no substitutions were performed. If no block and no replacement is given, an enumerator is returned instead.

    static VALUE
    rb_str_gsub_bang(int argc, VALUE *argv, VALUE str)
    {
        str_modify_keep_cr(str);
        return str_gsub(argc, argv, str, 1);
    }

hash → integer click to toggle source

Returns the integer hash value for `self`. The value is based on the length, content and encoding of `self`.

    static VALUE
    rb_str_hash_m(VALUE str)
    {
        st_index_t hval = rb_str_hash(str);
        return ST2FIX(hval);
    }

hex → integer click to toggle source

Treats leading characters from str as a string of hexadecimal digits (with an optional sign and an optional `0x`) and returns the corresponding number. Zero is returned on error.

    "0x0a".hex     #=> 10
    "-1234".hex    #=> -4660
    "0".hex        #=> 0
    "wombat".hex   #=> 0

    static VALUE
    rb_str_hex(VALUE str)
    {
        return rb_str_to_inum(str, 16, FALSE);
    }

include? other_str → true or false click to toggle source

Returns `true` if str contains the given string or character.

    "hello".include? "lo"   #=> true
    "hello".include? "ol"   #=> false
    "hello".include? ?h     #=> true

    static VALUE
    rb_str_include(VALUE str, VALUE arg)
    {
        long i;

        StringValue(arg);
        i = rb_str_index(str, arg, 0);

        if (i == -1) return Qfalse;
        return Qtrue;
    }

index(substring, offset = 0) → integer or nil click to toggle source
index(regexp, offset = 0) → integer or nil

Returns the Integer index of the first occurrence of the given `substring`, or `nil` if none found:

    'foo'.index('f') # => 0
    'foo'.index('o') # => 1
    'foo'.index('oo') # => 1
    'foo'.index('ooo') # => nil

Returns the Integer index of the first match for the given Regexp `regexp`, or `nil` if none found:

    'foo'.index(/f/) # => 0
    'foo'.index(/o/) # => 1
    'foo'.index(/oo/) # => 1
    'foo'.index(/ooo/) # => nil

Integer argument `offset`, if given, specifies the position in the string to begin the search:

    'foo'.index('o', 1) # => 1
    'foo'.index('o', 2) # => 2
    'foo'.index('o', 3) # => nil

If `offset` is negative, counts backward from the end of `self`:

    'foo'.index('o', -1) # => 2
    'foo'.index('o', -2) # => 1
    'foo'.index('o', -3) # => 1
    'foo'.index('o', -4) # => nil

Related: `String#rindex`

    static VALUE
    rb_str_index_m(int argc, VALUE *argv, VALUE str)
    {
        VALUE sub;
        VALUE initpos;
        long pos;

        if (rb_scan_args(argc, argv, "11", &sub, &initpos) == 2) {
            pos = NUM2LONG(initpos);
        }
        else {
            pos = 0;
        }
        if (pos < 0) {
            pos += str_strlen(str, NULL);
            if (pos < 0) {
                if (RB_TYPE_P(sub, T_REGEXP)) {
                    rb_backref_set(Qnil);
                }
                return Qnil;
            }
        }

        if (RB_TYPE_P(sub, T_REGEXP)) {
            if (pos > str_strlen(str, NULL))
                return Qnil;
            pos = str_offset(RSTRING_PTR(str), RSTRING_END(str), pos,
                             rb_enc_check(str, sub), single_byte_optimizable(str));

            if (rb_reg_search(sub, str, pos, 0) < 0) {
                return Qnil;
            } else {
                VALUE match = rb_backref_get();
                struct re_registers *regs = RMATCH_REGS(match);
                pos = rb_str_sublen(str, BEG(0));
                return LONG2NUM(pos);
            }
        }
        else {
            StringValue(sub);
            pos = rb_str_index(str, sub, pos);
            pos = rb_str_sublen(str, pos);
        }

        if (pos == -1) return Qnil;
        return LONG2NUM(pos);
    }

Replaces the contents of str with the corresponding values in other_str.

    s = "hello"         #=> "hello"
    s.replace "world"   #=> "world"

    VALUE
    rb_str_replace(VALUE str, VALUE str2)
    {
        str_modifiable(str);
        if (str == str2) return str;

        StringValue(str2);
        str_discard(str);
        return str_replace(str, str2);
    }

Also aliased as: replace
insert(index, other_string) → self click to toggle source

Inserts the given `other_string` into `self`; returns `self`.

If the Integer `index` is positive, inserts `other_string` at offset `index`:

    'foo'.insert(1, 'bar') # => "fbaroo"

If the Integer `index` is negative, counts backward from the end of `self` and inserts `other_string` at offset `index+1` (that is, after `self[index]`):

    'foo'.insert(-2, 'bar') # => "fobaro"

    static VALUE
    rb_str_insert(VALUE str, VALUE idx, VALUE str2)
    {
        long pos = NUM2LONG(idx);

        if (pos == -1) {
            return rb_str_append(str, str2);
        }
        else if (pos < 0) {
            pos++;
        }
        rb_str_splice(str, pos, 0, str2);
        return str;
    }

inspect → string click to toggle source

Returns a printable version of str, surrounded by quote marks, with special characters escaped.

    str = "hello"
    str[3] = "\b"
    str.inspect       #=> "\"hel\\bo\""

    VALUE
    rb_str_inspect(VALUE str)
    {
        int encidx = ENCODING_GET(str);
        rb_encoding *enc = rb_enc_from_index(encidx), *actenc;
        const char *p, *pend, *prev;
        char buf[CHAR_ESC_LEN + 1];
        VALUE result = rb_str_buf_new(0);
        rb_encoding *resenc = rb_default_internal_encoding();
        int unicode_p = rb_enc_unicode_p(enc);
        int asciicompat = rb_enc_asciicompat(enc);

        if (resenc == NULL) resenc = rb_default_external_encoding();
        if (!rb_enc_asciicompat(resenc)) resenc = rb_usascii_encoding();
        rb_enc_associate(result, resenc);
        str_buf_cat2(result, "\"");

        p = RSTRING_PTR(str); pend = RSTRING_END(str);
        prev = p;
        actenc = get_actual_encoding(encidx, str);
        if (actenc != enc) {
            enc = actenc;
            if (unicode_p) unicode_p = rb_enc_unicode_p(enc);
        }
        while (p < pend) {
            unsigned int c, cc;
            int n;

            n = rb_enc_precise_mbclen(p, pend, enc);
            if (!MBCLEN_CHARFOUND_P(n)) {
                if (p > prev) str_buf_cat(result, prev, p - prev);
                n = rb_enc_mbminlen(enc);
                if (pend < p + n)
                    n = (int)(pend - p);
                while (n--) {
                    snprintf(buf, CHAR_ESC_LEN, "\\x%02X", *p & 0377);
                    str_buf_cat(result, buf, strlen(buf));
                    prev = ++p;
                }
                continue;
            }
            n = MBCLEN_CHARFOUND_LEN(n);
            c = rb_enc_mbc_to_codepoint(p, pend, enc);
            p += n;
            if ((asciicompat || unicode_p) &&
              (c == '"'|| c == '\\' ||
                (c == '#' &&
                 p < pend &&
                 MBCLEN_CHARFOUND_P(rb_enc_precise_mbclen(p,pend,enc)) &&
                 (cc = rb_enc_codepoint(p,pend,enc),
                  (cc == '$' || cc == '@' || cc == '{'))))) {
                if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
                str_buf_cat2(result, "\\");
                if (asciicompat || enc == resenc) {
                    prev = p - n;
                    continue;
                }
            }
            switch (c) {
              case '\n': cc = 'n'; break;
              case '\r': cc = 'r'; break;
              case '\t': cc = 't'; break;
              case '\f': cc = 'f'; break;
              case '\013': cc = 'v'; break;
              case '\010': cc = 'b'; break;
              case '\007': cc = 'a'; break;
              case 033: cc = 'e'; break;
              default: cc = 0; break;
            }
            if (cc) {
                if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
                buf[0] = '\\';
                buf[1] = (char)cc;
                str_buf_cat(result, buf, 2);
                prev = p;
                continue;
            }
            if ((enc == resenc && rb_enc_isprint(c, enc)) ||
                (asciicompat && rb_enc_isascii(c, enc) && ISPRINT(c))) {
                continue;
            }
            else {
                if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
                rb_str_buf_cat_escaped_char(result, c, unicode_p);
                prev = p;
                continue;
            }
        }
        if (p > prev) str_buf_cat(result, prev, p - prev);
        str_buf_cat2(result, "\"");

        return result;
    }

intern → symbol click to toggle source

Returns the `Symbol` corresponding to str, creating the symbol if it did not previously exist. See `Symbol#id2name`.

    "Koala".intern         #=> :Koala
    s = 'cat'.to_sym       #=> :cat
    s == :cat              #=> true
    s = '@cat'.to_sym      #=> :@cat
    s == :@cat             #=> true

This can also be used to create symbols that cannot be represented using the `:xxx` notation.

    'cat and dog'.to_sym   #=> :"cat and dog"

    VALUE
    rb_str_intern(VALUE str)
    {
        VALUE sym;
    #if USE_SYMBOL_GC
        rb_encoding *enc, *ascii;
        int type;
    #else
        ID id;
    #endif
        GLOBAL_SYMBOLS_ENTER(symbols);
        {
            sym = lookup_str_sym_with_lock(symbols, str);

            if (sym) {
                // ok
            }
            else {
    #if USE_SYMBOL_GC
                enc = rb_enc_get(str);
                ascii = rb_usascii_encoding();
                if (enc != ascii && sym_check_asciionly(str)) {
                    str = rb_str_dup(str);
                    rb_enc_associate(str, ascii);
                    OBJ_FREEZE(str);
                    enc = ascii;
                }
                else {
                    str = rb_str_dup(str);
                    OBJ_FREEZE(str);
                }
                str = rb_fstring(str);
                type = rb_str_symname_type(str, IDSET_ATTRSET_FOR_INTERN);
                if (type < 0) type = ID_JUNK;
                sym = dsymbol_alloc(symbols, rb_cSymbol, str, enc, type);
    #else
                id = intern_str(str, 0);
                sym = ID2SYM(id);
    #endif
            }
        }
        GLOBAL_SYMBOLS_LEAVE();
        return sym;
    }

Also aliased as: to_sym
String#iseuc → true or false click to toggle source

Returns whether `self`'s encoding is EUC-JP or not.

    # File ext/nkf/lib/kconv.rb, line 264
    def iseuc;    Kconv.iseuc(self) end

String#isjis → true or false click to toggle source

Returns whether `self`'s encoding is ISO-2022-JP or not.

    # File ext/nkf/lib/kconv.rb, line 276
    def isjis;    Kconv.isjis(self) end

String#issjis → true or false click to toggle source

Returns whether `self`'s encoding is Shift_JIS or not.

    # File ext/nkf/lib/kconv.rb, line 270
    def issjis;   Kconv.issjis(self) end

String#isutf8 → true or false click to toggle source

Returns whether `self`'s encoding is UTF-8 or not.

    # File ext/nkf/lib/kconv.rb, line 282
    def isutf8;   Kconv.isutf8(self) end

String#kconv(to_enc, from_enc) click to toggle source

Convert `self` to `to_enc`. `to_enc` and `from_enc` are given as constants of `Kconv` or `Encoding` objects.

    # File ext/nkf/lib/kconv.rb, line 205
    def kconv(to_enc, from_enc=nil)
      from_enc = self.encoding if !from_enc && self.encoding != Encoding.list[0]
      Kconv::kconv(self, to_enc, from_enc)
    end

length → integer click to toggle source

Returns the count of characters (not bytes) in `self`:

    "\x80\u3042".length # => 2
    "hello".length # => 5

`String#size` is an alias for `String#length`.

Related: `String#bytesize`.

    VALUE
    rb_str_length(VALUE str)
    {
        return LONG2NUM(str_strlen(str, NULL));
    }

Also aliased as: size
lines(separator=$/, chomp: false) → an_array click to toggle source

Returns an array of lines in str split using the supplied record separator (`$/` by default). This is a shorthand for `str.each_line(separator, getline_args).to_a`.

If `chomp` is `true`, `separator` will be removed from the end of each line.

    "hello\nworld\n".lines              #=> ["hello\n", "world\n"]
    "hello  world".lines(' ')           #=> ["hello ", " ", "world"]
    "hello\nworld\n".lines(chomp: true) #=> ["hello", "world"]

If a block is given, which is a deprecated form, works the same as `each_line`.

    static VALUE
    rb_str_lines(int argc, VALUE *argv, VALUE str)
    {
        VALUE ary = WANTARRAY("lines", 0);
        return rb_str_enumerate_lines(argc, argv, str, ary);
    }

ljust(integer, padstr=' ') → new_str click to toggle source

If integer is greater than the length of str, returns a new `String` of length integer with str left justified and padded with padstr; otherwise, returns str.

    "hello".ljust(4)            #=> "hello"
    "hello".ljust(20)           #=> "hello               "
    "hello".ljust(20, '1234')   #=> "hello123412341234123"

    static VALUE
    rb_str_ljust(int argc, VALUE *argv, VALUE str)
    {
        return rb_str_justify(argc, argv, str, 'l');
    }

lstrip → new_str click to toggle source

Returns a copy of the receiver with leading whitespace removed. See also `String#rstrip` and `String#strip`.

Refer to `String#strip` for the definition of whitespace.

    "  hello  ".lstrip   #=> "hello  "
    "hello".lstrip       #=> "hello"

    static VALUE
    rb_str_lstrip(VALUE str)
    {
        char *start;
        long len, loffset;
        RSTRING_GETMEM(str, start, len);
        loffset = lstrip_offset(str, start, start+len, STR_ENC_GET(str));
        if (loffset <= 0) return str_duplicate(rb_cString, str);
        return rb_str_subseq(str, loffset, len - loffset);
    }

lstrip! → self or nil click to toggle source

Removes leading whitespace from the receiver. Returns the altered receiver, or `nil` if no change was made. See also `String#rstrip!` and `String#strip!`.

Refer to `String#strip` for the definition of whitespace.

    "  hello  ".lstrip!  #=> "hello  "
    "hello  ".lstrip!    #=> nil
    "hello".lstrip!      #=> nil

    static VALUE
    rb_str_lstrip_bang(VALUE str)
    {
        rb_encoding *enc;
        char *start, *s;
        long olen, loffset;

        str_modify_keep_cr(str);
        enc = STR_ENC_GET(str);
        RSTRING_GETMEM(str, start, olen);
        loffset = lstrip_offset(str, start, start+olen, enc);
        if (loffset > 0) {
            long len = olen-loffset;
            s = start + loffset;
            memmove(start, s, len);
            STR_SET_LEN(str, len);
    #if !SHARABLE_MIDDLE_SUBSTRING
            TERM_FILL(start+len, rb_enc_mbminlen(enc));
    #endif
            return str;
        }
        return Qnil;
    }

match(pattern, offset = 0) → matchdata or nil click to toggle source
match(pattern, offset = 0) {|matchdata| ... } → object

Returns a Matchdata object (or `nil`) based on `self` and the given `pattern`.

Note: also updates Regexp-related global variables.

- Computes `regexp` by converting `pattern` (if not already a Regexp).

      regexp = Regexp.new(pattern)

- Computes `matchdata`, which will be either a MatchData object or `nil` (see `Regexp#match`):

      matchdata = <tt>regexp.match(self)

With no block given, returns the computed `matchdata`:

    'foo'.match('f') # => #<MatchData "f">
    'foo'.match('o') # => #<MatchData "o">
    'foo'.match('x') # => nil

If Integer argument `offset` is given, the search begins at index `offset`:

    'foo'.match('f', 1) # => nil
    'foo'.match('o', 1) # => #<MatchData "o">

With a block given, calls the block with the computed `matchdata` and returns the block's return value:

    'foo'.match(/o/) {|matchdata| matchdata } # => #<MatchData "o">
    'foo'.match(/x/) {|matchdata| matchdata } # => nil
    'foo'.match(/f/, 1) {|matchdata| matchdata } # => nil

    static VALUE
    rb_str_match_m(int argc, VALUE *argv, VALUE str)
    {
        VALUE re, result;
        if (argc < 1)
            rb_check_arity(argc, 1, 2);
        re = argv[0];
        argv[0] = str;
        result = rb_funcallv(get_pat(re), rb_intern("match"), argc, argv);
        if (!NIL_P(result) && rb_block_given_p()) {
            return rb_yield(result);
        }
        return result;
    }

match?(pattern, offset = 0) → true or false click to toggle source

Returns `true` or `false` based on whether a match is found for `self` and `pattern`.

Note: does not update Regexp-related global variables.

Computes `regexp` by converting `pattern` (if not already a Regexp).

    regexp = Regexp.new(pattern)

Returns `true` if `self+.match(regexp)` returns a Matchdata object, `false` otherwise:

    'foo'.match?(/o/) # => true
    'foo'.match?('o') # => true
    'foo'.match?(/x/) # => false

If Integer argument `offset` is given, the search begins at index `offset`:

    'foo'.match?('f', 1) # => false
    'foo'.match?('o', 1) # => true

    static VALUE
    rb_str_match_m_p(int argc, VALUE *argv, VALUE str)
    {
        VALUE re;
        rb_check_arity(argc, 1, 2);
        re = get_pat(argv[0]);
        return rb_reg_match_p(re, str, argc > 1 ? NUM2LONG(argv[1]) : 0);
    }

Returns the successor to `self`. The successor is calculated by incrementing characters.

The first character to be incremented is the rightmost alphanumeric: or, if no alphanumerics, the rightmost character:

    'THX1138'.succ # => "THX1139"
    '<<koala>>'.succ # => "<<koalb>>"
    '***'.succ # => '**+'

The successor to a digit is another digit, “carrying” to the next-left character for a “rollover” from 9 to 0, and prepending another digit if necessary:

    '00'.succ # => "01"
    '09'.succ # => "10"
    '99'.succ # => "100"

The successor to a letter is another letter of the same case, carrying to the next-left character for a rollover, and prepending another same-case letter if necessary:

    'aa'.succ # => "ab"
    'az'.succ # => "ba"
    'zz'.succ # => "aaa"
    'AA'.succ # => "AB"
    'AZ'.succ # => "BA"
    'ZZ'.succ # => "AAA"

The successor to a non-alphanumeric character is the next character in the underlying character set's collating sequence, carrying to the next-left character for a rollover, and prepending another character if necessary:

    s = 0.chr * 3
    s # => "\x00\x00\x00"
    s.succ # => "\x00\x00\x01"
    s = 255.chr * 3
    s # => "\xFF\xFF\xFF"
    s.succ # => "\x01\x00\x00\x00"

Carrying can occur between and among mixtures of alphanumeric characters:

    s = 'zz99zz99'
    s.succ # => "aaa00aa00"
    s = '99zz99zz'
    s.succ # => "100aa00aa"

The successor to an empty String is a new empty String:

    ''.succ # => ""

`String#next` is an alias for `String#succ`.

Alias for: succ

Equivalent to `String#succ`, but modifies `self` in place; returns `self`.

`String#next!` is an alias for `String#succ!`.

Alias for: succ!
oct → integer click to toggle source

Treats leading characters of str as a string of octal digits (with an optional sign) and returns the corresponding number. Returns 0 if the conversion fails.

    "123".oct       #=> 83
    "-377".oct      #=> -255
    "bad".oct       #=> 0
    "0377bad".oct   #=> 255

If `str` starts with `0`, radix indicators are honored. See Kernel#Integer.

    static VALUE
    rb_str_oct(VALUE str)
    {
        return rb_str_to_inum(str, -8, FALSE);
    }

ord → integer click to toggle source

Returns the `Integer` ordinal of a one-character string.

    "a".ord         #=> 97

    static VALUE
    rb_str_ord(VALUE s)
    {
        unsigned int c;

        c = rb_enc_codepoint(RSTRING_PTR(s), RSTRING_END(s), STR_ENC_GET(s));
        return UINT2NUM(c);
    }

partition(sep) → [head, sep, tail] click to toggle source
partition(regexp) → [head, match, tail]

Searches sep or pattern (regexp) in the string and returns the part before it, the match, and the part after it. If it is not found, returns two empty strings and str.

    "hello".partition("l")         #=> ["he", "l", "lo"]
    "hello".partition("x")         #=> ["hello", "", ""]
    "hello".partition(/.l/)        #=> ["h", "el", "lo"]

    static VALUE
    rb_str_partition(VALUE str, VALUE sep)
    {
        long pos;

        sep = get_pat_quoted(sep, 0);
        if (RB_TYPE_P(sep, T_REGEXP)) {
            if (rb_reg_search(sep, str, 0, 0) < 0) {
                goto failed;
            }
            VALUE match = rb_backref_get();
            struct re_registers *regs = RMATCH_REGS(match);

            pos = BEG(0);
            sep = rb_str_subseq(str, pos, END(0) - pos);
        }
        else {
            pos = rb_str_index(str, sep, 0);
            if (pos < 0) goto failed;
        }
        return rb_ary_new3(3, rb_str_subseq(str, 0, pos),
                              sep,
                              rb_str_subseq(str, pos+RSTRING_LEN(sep),
                                                 RSTRING_LEN(str)-pos-RSTRING_LEN(sep)));

      failed:
        return rb_ary_new3(3, str_duplicate(rb_cString, str), str_new_empty_String(str), str_new_empty_String(str));
    }

prepend(*other_strings) → str click to toggle source

Returns a new String containing the concatenation of all given `other_strings` and `self`:

    s = 'foo'
    s.prepend('bar', 'baz') # => "barbazfoo"

Related: `String#concat`.

    static VALUE
    rb_str_prepend_multi(int argc, VALUE *argv, VALUE str)
    {
        str_modifiable(str);

        if (argc == 1) {
            rb_str_update(str, 0L, 0L, argv[0]);
        }
        else if (argc > 1) {
            int i;
            VALUE arg_str = rb_str_tmp_new(0);
            rb_enc_copy(arg_str, str);
            for (i = 0; i < argc; i++) {
                rb_str_append(arg_str, argv[i]);
            }
            rb_str_update(str, 0L, 0L, arg_str);
        }

        return str;
    }

replace(other_str) → str

Replaces the contents of str with the corresponding values in other_str.

    s = "hello"         #=> "hello"
    s.replace "world"   #=> "world"

Alias for: initialize_copy
reverse → new_str click to toggle source

Returns a new string with the characters from str in reverse order.

    "stressed".reverse   #=> "desserts"

    static VALUE
    rb_str_reverse(VALUE str)
    {
        rb_encoding *enc;
        VALUE rev;
        char *s, *e, *p;
        int cr;

        if (RSTRING_LEN(str) <= 1) return str_duplicate(rb_cString, str);
        enc = STR_ENC_GET(str);
        rev = rb_str_new(0, RSTRING_LEN(str));
        s = RSTRING_PTR(str); e = RSTRING_END(str);
        p = RSTRING_END(rev);
        cr = ENC_CODERANGE(str);

        if (RSTRING_LEN(str) > 1) {
            if (single_byte_optimizable(str)) {
                while (s < e) {
                    *--p = *s++;
                }
            }
            else if (cr == ENC_CODERANGE_VALID) {
                while (s < e) {
                    int clen = rb_enc_fast_mbclen(s, e, enc);

                    p -= clen;
                    memcpy(p, s, clen);
                    s += clen;
                }
            }
            else {
                cr = rb_enc_asciicompat(enc) ?
                    ENC_CODERANGE_7BIT : ENC_CODERANGE_VALID;
                while (s < e) {
                    int clen = rb_enc_mbclen(s, e, enc);

                    if (clen > 1 || (*s & 0x80)) cr = ENC_CODERANGE_UNKNOWN;
                    p -= clen;
                    memcpy(p, s, clen);
                    s += clen;
                }
            }
        }
        STR_SET_LEN(rev, RSTRING_LEN(str));
        str_enc_copy(rev, str);
        ENC_CODERANGE_SET(rev, cr);

        return rev;
    }

reverse! → str click to toggle source

Reverses str in place.

    static VALUE
    rb_str_reverse_bang(VALUE str)
    {
        if (RSTRING_LEN(str) > 1) {
            if (single_byte_optimizable(str)) {
                char *s, *e, c;

                str_modify_keep_cr(str);
                s = RSTRING_PTR(str);
                e = RSTRING_END(str) - 1;
                while (s < e) {
                    c = *s;
                    *s++ = *e;
                    *e-- = c;
                }
            }
            else {
                str_shared_replace(str, rb_str_reverse(str));
            }
        }
        else {
            str_modify_keep_cr(str);
        }
        return str;
    }

rindex(substring, offset = self.length) → integer or nil click to toggle source
rindex(regexp, offset = self.length) → integer or nil

Returns the Integer index of the last occurrence of the given `substring`, or `nil` if none found:

    'foo'.rindex('f') # => 0
    'foo'.rindex('o') # => 2
    'foo'.rindex('oo') # => 1
    'foo'.rindex('ooo') # => nil

Returns the Integer index of the last match for the given Regexp `regexp`, or `nil` if none found:

    'foo'.rindex(/f/) # => 0
    'foo'.rindex(/o/) # => 2
    'foo'.rindex(/oo/) # => 1
    'foo'.rindex(/ooo/) # => nil

Integer argument `offset`, if given and non-negative, specifies the maximum starting position in the

    string to _end_ the search:
     'foo'.rindex('o', 0) # => nil
     'foo'.rindex('o', 1) # => 1
     'foo'.rindex('o', 2) # => 2
     'foo'.rindex('o', 3) # => 2

If `offset` is a negative Integer, the maximum starting position in the string to end the search is the sum of the string's length and `offset`:

    'foo'.rindex('o', -1) # => 2
    'foo'.rindex('o', -2) # => 1
    'foo'.rindex('o', -3) # => nil
    'foo'.rindex('o', -4) # => nil

Related: `String#index`

    static VALUE
    rb_str_rindex_m(int argc, VALUE *argv, VALUE str)
    {
        VALUE sub;
        VALUE vpos;
        rb_encoding *enc = STR_ENC_GET(str);
        long pos, len = str_strlen(str, enc); /* str's enc */

        if (rb_scan_args(argc, argv, "11", &sub, &vpos) == 2) {
            pos = NUM2LONG(vpos);
            if (pos < 0) {
                pos += len;
                if (pos < 0) {
                    if (RB_TYPE_P(sub, T_REGEXP)) {
                        rb_backref_set(Qnil);
                    }
                    return Qnil;
                }
            }
            if (pos > len) pos = len;
        }
        else {
            pos = len;
        }

        if (RB_TYPE_P(sub, T_REGEXP)) {
            /* enc = rb_get_check(str, sub); */
            pos = str_offset(RSTRING_PTR(str), RSTRING_END(str), pos,
                             enc, single_byte_optimizable(str));

            if (rb_reg_search(sub, str, pos, 1) >= 0) {
                VALUE match = rb_backref_get();
                struct re_registers *regs = RMATCH_REGS(match);
                pos = rb_str_sublen(str, BEG(0));
                return LONG2NUM(pos);
            }
        }
        else {
            StringValue(sub);
            pos = rb_str_rindex(str, sub, pos);
            if (pos >= 0) return LONG2NUM(pos);
        }
        return Qnil;
    }

rjust(integer, padstr=' ') → new_str click to toggle source

If integer is greater than the length of str, returns a new `String` of length integer with str right justified and padded with padstr; otherwise, returns str.

    "hello".rjust(4)            #=> "hello"
    "hello".rjust(20)           #=> "               hello"
    "hello".rjust(20, '1234')   #=> "123412341234123hello"

    static VALUE
    rb_str_rjust(int argc, VALUE *argv, VALUE str)
    {
        return rb_str_justify(argc, argv, str, 'r');
    }

rpartition(sep) → [head, sep, tail] click to toggle source
rpartition(regexp) → [head, match, tail]

Searches sep or pattern (regexp) in the string from the end of the string, and returns the part before it, the match, and the part after it. If it is not found, returns two empty strings and str.

    "hello".rpartition("l")         #=> ["hel", "l", "o"]
    "hello".rpartition("x")         #=> ["", "", "hello"]
    "hello".rpartition(/.l/)        #=> ["he", "ll", "o"]

    static VALUE
    rb_str_rpartition(VALUE str, VALUE sep)
    {
        long pos = RSTRING_LEN(str);

        sep = get_pat_quoted(sep, 0);
        if (RB_TYPE_P(sep, T_REGEXP)) {
            if (rb_reg_search(sep, str, pos, 1) < 0) {
                goto failed;
            }
            VALUE match = rb_backref_get();
            struct re_registers *regs = RMATCH_REGS(match);

            pos = BEG(0);
            sep = rb_str_subseq(str, pos, END(0) - pos);
        }
        else {
            pos = rb_str_sublen(str, pos);
            pos = rb_str_rindex(str, sep, pos);
            if(pos < 0) {
                goto failed;
            }
            pos = rb_str_offset(str, pos);
        }

        return rb_ary_new3(3, rb_str_subseq(str, 0, pos),
                              sep,
                              rb_str_subseq(str, pos+RSTRING_LEN(sep),
                                            RSTRING_LEN(str)-pos-RSTRING_LEN(sep)));
      failed:
        return rb_ary_new3(3, str_new_empty_String(str), str_new_empty_String(str), str_duplicate(rb_cString, str));
    }

rstrip → new_str click to toggle source

Returns a copy of the receiver with trailing whitespace removed. See also `String#lstrip` and `String#strip`.

Refer to `String#strip` for the definition of whitespace.

    "  hello  ".rstrip   #=> "  hello"
    "hello".rstrip       #=> "hello"

    static VALUE
    rb_str_rstrip(VALUE str)
    {
        rb_encoding *enc;
        char *start;
        long olen, roffset;

        enc = STR_ENC_GET(str);
        RSTRING_GETMEM(str, start, olen);
        roffset = rstrip_offset(str, start, start+olen, enc);

        if (roffset <= 0) return str_duplicate(rb_cString, str);
        return rb_str_subseq(str, 0, olen-roffset);
    }

rstrip! → self or nil click to toggle source

Removes trailing whitespace from the receiver. Returns the altered receiver, or `nil` if no change was made. See also `String#lstrip!` and `String#strip!`.

Refer to `String#strip` for the definition of whitespace.

    "  hello  ".rstrip!  #=> "  hello"
    "  hello".rstrip!    #=> nil
    "hello".rstrip!      #=> nil

    static VALUE
    rb_str_rstrip_bang(VALUE str)
    {
        rb_encoding *enc;
        char *start;
        long olen, roffset;

        str_modify_keep_cr(str);
        enc = STR_ENC_GET(str);
        RSTRING_GETMEM(str, start, olen);
        roffset = rstrip_offset(str, start, start+olen, enc);
        if (roffset > 0) {
            long len = olen - roffset;

            STR_SET_LEN(str, len);
    #if !SHARABLE_MIDDLE_SUBSTRING
            TERM_FILL(start+len, rb_enc_mbminlen(enc));
    #endif
            return str;
        }
        return Qnil;
    }

scan(pattern) → array click to toggle source
scan(pattern) {|match, ...| block } → str

Both forms iterate through str, matching the pattern (which may be a `Regexp` or a `String`). For each match, a result is generated and either added to the result array or passed to the block. If the pattern contains no groups, each individual result consists of the matched string, `$&`. If the pattern contains groups, each individual result is itself an array containing one entry per group.

    a = "cruel world"
    a.scan(/\w+/)        #=> ["cruel", "world"]
    a.scan(/.../)        #=> ["cru", "el ", "wor"]
    a.scan(/(...)/)      #=> [["cru"], ["el "], ["wor"]]
    a.scan(/(..)(..)/)   #=> [["cr", "ue"], ["l ", "wo"]]

And the block form:

    a.scan(/\w+/) {|w| print "<<#{w}>> " }
    print "\n"
    a.scan(/(.)(.)/) {|x,y| print y, x }
    print "\n"

produces:

    <<cruel>> <<world>>
    rceu lowlr

    static VALUE
    rb_str_scan(VALUE str, VALUE pat)
    {
        VALUE result;
        long start = 0;
        long last = -1, prev = 0;
        char *p = RSTRING_PTR(str); long len = RSTRING_LEN(str);

        pat = get_pat_quoted(pat, 1);
        mustnot_broken(str);
        if (!rb_block_given_p()) {
            VALUE ary = rb_ary_new();

            while (!NIL_P(result = scan_once(str, pat, &start, 0))) {
                last = prev;
                prev = start;
                rb_ary_push(ary, result);
            }
            if (last >= 0) rb_pat_search(pat, str, last, 1);
            else rb_backref_set(Qnil);
            return ary;
        }

        while (!NIL_P(result = scan_once(str, pat, &start, 1))) {
            last = prev;
            prev = start;
            rb_yield(result);
            str_mod_check(str, p, len);
        }
        if (last >= 0) rb_pat_search(pat, str, last, 1);
        return str;
    }

scrub → new_str click to toggle source
scrub(repl) → new_str
scrub{|bytes|} → new_str

If the string is invalid byte sequence then replace invalid bytes with given replacement character, else returns self. If block is given, replace invalid bytes with returned value of the block.

    "abc\u3042\x81".scrub #=> "abc\u3042\uFFFD"
    "abc\u3042\x81".scrub("*") #=> "abc\u3042*"
    "abc\u3042\xE3\x80".scrub{|bytes| '<'+bytes.unpack('H*')[0]+'>' } #=> "abc\u3042<e380>"

    static VALUE
    str_scrub(int argc, VALUE *argv, VALUE str)
    {
        VALUE repl = argc ? (rb_check_arity(argc, 0, 1), argv[0]) : Qnil;
        VALUE new = rb_str_scrub(str, repl);
        return NIL_P(new) ? str_duplicate(rb_cString, str): new;
    }

scrub! → str click to toggle source
scrub!(repl) → str
scrub!{|bytes|} → str

If the string is invalid byte sequence then replace invalid bytes with given replacement character, else returns self. If block is given, replace invalid bytes with returned value of the block.

    "abc\u3042\x81".scrub! #=> "abc\u3042\uFFFD"
    "abc\u3042\x81".scrub!("*") #=> "abc\u3042*"
    "abc\u3042\xE3\x80".scrub!{|bytes| '<'+bytes.unpack('H*')[0]+'>' } #=> "abc\u3042<e380>"

    static VALUE
    str_scrub_bang(int argc, VALUE *argv, VALUE str)
    {
        VALUE repl = argc ? (rb_check_arity(argc, 0, 1), argv[0]) : Qnil;
        VALUE new = rb_str_scrub(str, repl);
        if (!NIL_P(new)) rb_str_replace(str, new);
        return str;
    }

setbyte(index, integer) → integer click to toggle source

modifies the indexth byte as integer.

    static VALUE
    rb_str_setbyte(VALUE str, VALUE index, VALUE value)
    {
        long pos = NUM2LONG(index);
        long len = RSTRING_LEN(str);
        char *head, *left = 0;
        unsigned char *ptr;
        rb_encoding *enc;
        int cr = ENC_CODERANGE_UNKNOWN, width, nlen;

        if (pos < -len || len <= pos)
            rb_raise(rb_eIndexError, "index %ld out of string", pos);
        if (pos < 0)
            pos += len;

        VALUE v = rb_to_int(value);
        VALUE w = rb_int_and(v, INT2FIX(0xff));
        unsigned char byte = NUM2INT(w) & 0xFF;

        if (!str_independent(str))
            str_make_independent(str);
        enc = STR_ENC_GET(str);
        head = RSTRING_PTR(str);
        ptr = (unsigned char *)&head[pos];
        if (!STR_EMBED_P(str)) {
            cr = ENC_CODERANGE(str);
            switch (cr) {
              case ENC_CODERANGE_7BIT:
                left = (char *)ptr;
                *ptr = byte;
                if (ISASCII(byte)) goto end;
                nlen = rb_enc_precise_mbclen(left, head+len, enc);
                if (!MBCLEN_CHARFOUND_P(nlen))
                    ENC_CODERANGE_SET(str, ENC_CODERANGE_BROKEN);
                else
                    ENC_CODERANGE_SET(str, ENC_CODERANGE_VALID);
                goto end;
              case ENC_CODERANGE_VALID:
                left = rb_enc_left_char_head(head, ptr, head+len, enc);
                width = rb_enc_precise_mbclen(left, head+len, enc);
                *ptr = byte;
                nlen = rb_enc_precise_mbclen(left, head+len, enc);
                if (!MBCLEN_CHARFOUND_P(nlen))
                    ENC_CODERANGE_SET(str, ENC_CODERANGE_BROKEN);
                else if (MBCLEN_CHARFOUND_LEN(nlen) != width || ISASCII(byte))
                    ENC_CODERANGE_CLEAR(str);
                goto end;
            }
        }
        ENC_CODERANGE_CLEAR(str);
        *ptr = byte;

      end:
        return value;
    }

shellescape → string click to toggle source

Escapes `str` so that it can be safely used in a Bourne shell command line.

See `Shellwords.shellescape` for details.

    # File lib/shellwords.rb, line 224
    def shellescape
      Shellwords.escape(self)
    end

shellsplit → array click to toggle source

Splits `str` into an array of tokens in the same way the UNIX Bourne shell does.

See `Shellwords.shellsplit` for details.

    # File lib/shellwords.rb, line 213
    def shellsplit
      Shellwords.split(self)
    end

Returns the count of characters (not bytes) in `self`:

    "\x80\u3042".length # => 2
    "hello".length # => 5

`String#size` is an alias for `String#length`.

Related: `String#bytesize`.

Alias for: length

Returns the substring of `self` specified by the arguments.

When the single Integer argument `index` is given, returns the 1-character substring found in `self` at offset `index`:

    'bar'[2] # => "r"

Counts backward from the end of `self` if `index` is negative:

    'foo'[-3] # => "f"

Returns `nil` if `index` is out of range:

    'foo'[3] # => nil
    'foo'[-4] # => nil

When the two Integer arguments `start` and `length` are given, returns the substring of the given `length` found in `self` at offset `start`:

    'foo'[0, 2] # => "fo"
    'foo'[0, 0] # => ""

Counts backward from the end of `self` if `start` is negative:

    'foo'[-2, 2] # => "oo"

Special case: returns a new empty String if `start` is equal to the length of `self`:

    'foo'[3, 2] # => ""

Returns `nil` if `start` is out of range:

    'foo'[4, 2] # => nil
    'foo'[-4, 2] # => nil

Returns the trailing substring of `self` if `length` is large:

    'foo'[1, 50] # => "oo"

Returns `nil` if `length` is negative:

    'foo'[0, -1] # => nil

When the single Range argument `range` is given, derives `start` and `length` values from the given `range`, and returns values as above:

- `'foo'[0..1]` is equivalent to `'foo'[0, 2]`.

- `'foo'[0...1]` is equivalent to `'foo'[0, 1]`.

When the Regexp argument `regexp` is given, and the `capture` argument is `0`, returns the first matching substring found in `self`, or `nil` if none found:

    'foo'[/o/] # => "o"
    'foo'[/x/] # => nil
    s = 'hello there'
    s[/[aeiou](.)\1/] # => "ell"
    s[/[aeiou](.)\1/, 0] # => "ell"

If argument `capture` is given and not `0`, it should be either an Integer capture group index or a String or Symbol capture group name; the method call returns only the specified capture (see Regexp Capturing):

    s = 'hello there'
    s[/[aeiou](.)\1/, 1] # => "l"
    s[/(?<vowel>[aeiou])(?<non_vowel>[^aeiou])/, "non_vowel"] # => "l"
    s[/(?<vowel>[aeiou])(?<non_vowel>[^aeiou])/, :vowel] # => "e"

If an invalid capture group index is given, `nil` is returned. If an invalid capture group name is given, `IndexError` is raised.

When the single String argument `substring` is given, returns the substring from `self` if found, otherwise `nil`:

    'foo'['oo'] # => "oo"
    'foo'['xx'] # => nil

`String#slice` is an alias for `String#[]`.

Alias for: []
slice!(integer) → new_str or nil click to toggle source
slice!(integer, integer) → new_str or nil
slice!(range) → new_str or nil
slice!(regexp) → new_str or nil
slice!(other_str) → new_str or nil

Deletes the specified portion from str, and returns the portion deleted.

    string = "this is a string"
    string.slice!(2)        #=> "i"
    string.slice!(3..6)     #=> " is "
    string.slice!(/s.*t/)   #=> "sa st"
    string.slice!("r")      #=> "r"
    string                  #=> "thing"

    static VALUE
    rb_str_slice_bang(int argc, VALUE *argv, VALUE str)
    {
        VALUE result = Qnil;
        VALUE indx;
        long beg, len = 1;
        char *p;

        rb_check_arity(argc, 1, 2);
        str_modify_keep_cr(str);
        indx = argv[0];
        if (RB_TYPE_P(indx, T_REGEXP)) {
            if (rb_reg_search(indx, str, 0, 0) < 0) return Qnil;
            VALUE match = rb_backref_get();
            struct re_registers *regs = RMATCH_REGS(match);
            int nth = 0;
            if (argc > 1 && (nth = rb_reg_backref_number(match, argv[1])) < 0) {
                if ((nth += regs->num_regs) <= 0) return Qnil;
            }
            else if (nth >= regs->num_regs) return Qnil;
            beg = BEG(nth);
            len = END(nth) - beg;
            goto subseq;
        }
        else if (argc == 2) {
            beg = NUM2LONG(indx);
            len = NUM2LONG(argv[1]);
            goto num_index;
        }
        else if (FIXNUM_P(indx)) {
            beg = FIX2LONG(indx);
            if (!(p = rb_str_subpos(str, beg, &len))) return Qnil;
            if (!len) return Qnil;
            beg = p - RSTRING_PTR(str);
            goto subseq;
        }
        else if (RB_TYPE_P(indx, T_STRING)) {
            beg = rb_str_index(str, indx, 0);
            if (beg == -1) return Qnil;
            len = RSTRING_LEN(indx);
            result = str_duplicate(rb_cString, indx);
            goto squash;
        }
        else {
            switch (rb_range_beg_len(indx, &beg, &len, str_strlen(str, NULL), 0)) {
              case Qnil:
                return Qnil;
              case Qfalse:
                beg = NUM2LONG(indx);
                if (!(p = rb_str_subpos(str, beg, &len))) return Qnil;
                if (!len) return Qnil;
                beg = p - RSTRING_PTR(str);
                goto subseq;
              default:
                goto num_index;
            }
        }

      num_index:
        if (!(p = rb_str_subpos(str, beg, &len))) return Qnil;
        beg = p - RSTRING_PTR(str);

      subseq:
        result = rb_str_new(RSTRING_PTR(str)+beg, len);
        rb_enc_cr_str_copy_for_substr(result, str);

      squash:
        if (len > 0) {
            if (beg == 0) {
                rb_str_drop_bytes(str, len);
            }
            else {
                char *sptr = RSTRING_PTR(str);
                long slen = RSTRING_LEN(str);
                if (beg + len > slen) /* pathological check */
                    len = slen - beg;
                memmove(sptr + beg,
                        sptr + beg + len,
                        slen - (beg + len));
                slen -= len;
                STR_SET_LEN(str, slen);
                TERM_FILL(&sptr[slen], TERM_LEN(str));
            }
        }
        return result;
    }

split(pattern=nil, [limit]) → an_array click to toggle source
split(pattern=nil, [limit]) {|sub| block } → str

Divides str into substrings based on a delimiter, returning an array of these substrings.

If pattern is a `String`, then its contents are used as the delimiter when splitting str. If pattern is a single space, str is split on whitespace, with leading and trailing whitespace and runs of contiguous whitespace characters ignored.

If pattern is a `Regexp`, str is divided where the pattern matches. Whenever the pattern matches a zero-length string, str is split into individual characters. If pattern contains groups, the respective matches will be returned in the array as well.

If pattern is `nil`, the value of `$;` is used. If `$;` is `nil` (which is the default), str is split on whitespace as if ' ' were specified.

If the limit parameter is omitted, trailing null fields are suppressed. If limit is a positive number, at most that number of split substrings will be returned (captured groups will be returned as well, but are not counted towards the limit). If limit is `1`, the entire string is returned as the only entry in an array. If negative, there is no limit to the number of fields returned, and trailing null fields are not suppressed.

When the input `str` is empty an empty `Array` is returned as the string is considered to have no fields to split.

    " now's  the time ".split       #=> ["now's", "the", "time"]
    " now's  the time ".split(' ')  #=> ["now's", "the", "time"]
    " now's  the time".split(/ /)   #=> ["", "now's", "", "the", "time"]
    "1, 2.34,56, 7".split(%r{,\s*}) #=> ["1", "2.34", "56", "7"]
    "hello".split(//)               #=> ["h", "e", "l", "l", "o"]
    "hello".split(//, 3)            #=> ["h", "e", "llo"]
    "hi mom".split(%r{\s*})         #=> ["h", "i", "m", "o", "m"]

    "mellow yellow".split("ello")   #=> ["m", "w y", "w"]
    "1,2,,3,4,,".split(',')         #=> ["1", "2", "", "3", "4"]
    "1,2,,3,4,,".split(',', 4)      #=> ["1", "2", "", "3,4,,"]
    "1,2,,3,4,,".split(',', -4)     #=> ["1", "2", "", "3", "4", "", ""]

    "1:2:3".split(/(:)()()/, 2)     #=> ["1", ":", "", "", "2:3"]

    "".split(',', -1)               #=> []

If a block is given, invoke the block with each split substring.

    static VALUE
    rb_str_split_m(int argc, VALUE *argv, VALUE str)
    {
        rb_encoding *enc;
        VALUE spat;
        VALUE limit;
        split_type_t split_type;
        long beg, end, i = 0, empty_count = -1;
        int lim = 0;
        VALUE result, tmp;

        result = rb_block_given_p() ? Qfalse : Qnil;
        if (rb_scan_args(argc, argv, "02", &spat, &limit) == 2) {
            lim = NUM2INT(limit);
            if (lim <= 0) limit = Qnil;
            else if (lim == 1) {
                if (RSTRING_LEN(str) == 0)
                    return result ? rb_ary_new2(0) : str;
                tmp = str_duplicate(rb_cString, str);
                if (!result) {
                    rb_yield(tmp);
                    return str;
                }
                return rb_ary_new3(1, tmp);
            }
            i = 1;
        }
        if (NIL_P(limit) && !lim) empty_count = 0;

        enc = STR_ENC_GET(str);
        split_type = SPLIT_TYPE_REGEXP;
        if (!NIL_P(spat)) {
            spat = get_pat_quoted(spat, 0);
        }
        else if (NIL_P(spat = rb_fs)) {
            split_type = SPLIT_TYPE_AWK;
        }
        else if (!(spat = rb_fs_check(spat))) {
            rb_raise(rb_eTypeError, "value of $; must be String or Regexp");
        }
        else {
            rb_category_warn(RB_WARN_CATEGORY_DEPRECATED, "$; is set to non-nil value");
        }
        if (split_type != SPLIT_TYPE_AWK) {
            switch (BUILTIN_TYPE(spat)) {
              case T_REGEXP:
                rb_reg_options(spat); /* check if uninitialized */
                tmp = RREGEXP_SRC(spat);
                split_type = literal_split_pattern(tmp, SPLIT_TYPE_REGEXP);
                if (split_type == SPLIT_TYPE_AWK) {
                    spat = tmp;
                    split_type = SPLIT_TYPE_STRING;
                }
                break;

              case T_STRING:
                mustnot_broken(spat);
                split_type = literal_split_pattern(spat, SPLIT_TYPE_STRING);
                break;

              default:
                UNREACHABLE_RETURN(Qnil);
            }
        }

    #define SPLIT_STR(beg, len) (empty_count = split_string(result, str, beg, len, empty_count))

        if (result) result = rb_ary_new();
        beg = 0;
        char *ptr = RSTRING_PTR(str);
        char *eptr = RSTRING_END(str);
        if (split_type == SPLIT_TYPE_AWK) {
            char *bptr = ptr;
            int skip = 1;
            unsigned int c;

            end = beg;
            if (is_ascii_string(str)) {
                while (ptr < eptr) {
                    c = (unsigned char)*ptr++;
                    if (skip) {
                        if (ascii_isspace(c)) {
                            beg = ptr - bptr;
                        }
                        else {
                            end = ptr - bptr;
                            skip = 0;
                            if (!NIL_P(limit) && lim <= i) break;
                        }
                    }
                    else if (ascii_isspace(c)) {
                        SPLIT_STR(beg, end-beg);
                        skip = 1;
                        beg = ptr - bptr;
                        if (!NIL_P(limit)) ++i;
                    }
                    else {
                        end = ptr - bptr;
                    }
                }
            }
            else {
                while (ptr < eptr) {
                    int n;

                    c = rb_enc_codepoint_len(ptr, eptr, &n, enc);
                    ptr += n;
                    if (skip) {
                        if (rb_isspace(c)) {
                            beg = ptr - bptr;
                        }
                        else {
                            end = ptr - bptr;
                            skip = 0;
                            if (!NIL_P(limit) && lim <= i) break;
                        }
                    }
                    else if (rb_isspace(c)) {
                        SPLIT_STR(beg, end-beg);
                        skip = 1;
                        beg = ptr - bptr;
                        if (!NIL_P(limit)) ++i;
                    }
                    else {
                        end = ptr - bptr;
                    }
                }
            }
        }
        else if (split_type == SPLIT_TYPE_STRING) {
            char *str_start = ptr;
            char *substr_start = ptr;
            char *sptr = RSTRING_PTR(spat);
            long slen = RSTRING_LEN(spat);

            mustnot_broken(str);
            enc = rb_enc_check(str, spat);
            while (ptr < eptr &&
                   (end = rb_memsearch(sptr, slen, ptr, eptr - ptr, enc)) >= 0) {
                /* Check we are at the start of a char */
                char *t = rb_enc_right_char_head(ptr, ptr + end, eptr, enc);
                if (t != ptr + end) {
                    ptr = t;
                    continue;
                }
                SPLIT_STR(substr_start - str_start, (ptr+end) - substr_start);
                ptr += end + slen;
                substr_start = ptr;
                if (!NIL_P(limit) && lim <= ++i) break;
            }
            beg = ptr - str_start;
        }
        else if (split_type == SPLIT_TYPE_CHARS) {
            char *str_start = ptr;
            int n;

            mustnot_broken(str);
            enc = rb_enc_get(str);
            while (ptr < eptr &&
                   (n = rb_enc_precise_mbclen(ptr, eptr, enc)) > 0) {
                SPLIT_STR(ptr - str_start, n);
                ptr += n;
                if (!NIL_P(limit) && lim <= ++i) break;
            }
            beg = ptr - str_start;
        }
        else {
            long len = RSTRING_LEN(str);
            long start = beg;
            long idx;
            int last_null = 0;
            struct re_registers *regs;
            VALUE match = 0;

            for (; rb_reg_search(spat, str, start, 0) >= 0;
                 (match ? (rb_match_unbusy(match), rb_backref_set(match)) : (void)0)) {
                match = rb_backref_get();
                if (!result) rb_match_busy(match);
                regs = RMATCH_REGS(match);
                end = BEG(0);
                if (start == end && BEG(0) == END(0)) {
                    if (!ptr) {
                        SPLIT_STR(0, 0);
                        break;
                    }
                    else if (last_null == 1) {
                        SPLIT_STR(beg, rb_enc_fast_mbclen(ptr+beg, eptr, enc));
                        beg = start;
                    }
                    else {
                        if (start == len)
                            start++;
                        else
                            start += rb_enc_fast_mbclen(ptr+start,eptr,enc);
                        last_null = 1;
                        continue;
                    }
                }
                else {
                    SPLIT_STR(beg, end-beg);
                    beg = start = END(0);
                }
                last_null = 0;

                for (idx=1; idx < regs->num_regs; idx++) {
                    if (BEG(idx) == -1) continue;
                    SPLIT_STR(BEG(idx), END(idx)-BEG(idx));
                }
                if (!NIL_P(limit) && lim <= ++i) break;
            }
            if (match) rb_match_unbusy(match);
        }
        if (RSTRING_LEN(str) > 0 && (!NIL_P(limit) || RSTRING_LEN(str) > beg || lim < 0)) {
            SPLIT_STR(beg, RSTRING_LEN(str)-beg);
        }

        return result ? result : str;
    }

squeeze([other_str]*) → new_str click to toggle source

Builds a set of characters from the other_str parameter(s) using the procedure described for `String#count`. Returns a new string where runs of the same character that occur in this set are replaced by a single character. If no arguments are given, all runs of identical characters are replaced by a single character.

    "yellow moon".squeeze                  #=> "yelow mon"
    "  now   is  the".squeeze(" ")         #=> " now is the"
    "putters shoot balls".squeeze("m-z")   #=> "puters shot balls"

    static VALUE
    rb_str_squeeze(int argc, VALUE *argv, VALUE str)
    {
        str = str_duplicate(rb_cString, str);
        rb_str_squeeze_bang(argc, argv, str);
        return str;
    }

squeeze!([other_str]*) → str or nil click to toggle source

Squeezes str in place, returning either str, or `nil` if no changes were made.

    static VALUE
    rb_str_squeeze_bang(int argc, VALUE *argv, VALUE str)
    {
        char squeez[TR_TABLE_SIZE];
        rb_encoding *enc = 0;
        VALUE del = 0, nodel = 0;
        unsigned char *s, *send, *t;
        int i, modify = 0;
        int ascompat, singlebyte = single_byte_optimizable(str);
        unsigned int save;

        if (argc == 0) {
            enc = STR_ENC_GET(str);
        }
        else {
            for (i=0; i<argc; i++) {
                VALUE s = argv[i];

                StringValue(s);
                enc = rb_enc_check(str, s);
                if (singlebyte && !single_byte_optimizable(s))
                    singlebyte = 0;
                tr_setup_table(s, squeez, i==0, &del, &nodel, enc);
            }
        }

        str_modify_keep_cr(str);
        s = t = (unsigned char *)RSTRING_PTR(str);
        if (!s || RSTRING_LEN(str) == 0) return Qnil;
        send = (unsigned char *)RSTRING_END(str);
        save = -1;
        ascompat = rb_enc_asciicompat(enc);

        if (singlebyte) {
            while (s < send) {
                unsigned int c = *s++;
                if (c != save || (argc > 0 && !squeez[c])) {
                    *t++ = save = c;
                }
            }
        }
        else {
            while (s < send) {
                unsigned int c;
                int clen;

                if (ascompat && (c = *s) < 0x80) {
                    if (c != save || (argc > 0 && !squeez[c])) {
                        *t++ = save = c;
                    }
                    s++;
                }
                else {
                    c = rb_enc_codepoint_len((char *)s, (char *)send, &clen, enc);

                    if (c != save || (argc > 0 && !tr_find(c, squeez, del, nodel))) {
                        if (t != s) rb_enc_mbcput(c, t, enc);
                        save = c;
                        t += clen;
                    }
                    s += clen;
                }
            }
        }

        TERM_FILL((char *)t, TERM_LEN(str));
        if ((char *)t - RSTRING_PTR(str) != RSTRING_LEN(str)) {
            STR_SET_LEN(str, (char *)t - RSTRING_PTR(str));
            modify = 1;
        }

        if (modify) return str;
        return Qnil;
    }

start_with?([prefixes]+) → true or false click to toggle source

Returns true if `str` starts with one of the `prefixes` given. Each of the `prefixes` should be a `String` or a `Regexp`.

    "hello".start_with?("hell")               #=> true
    "hello".start_with?(/H/i)                 #=> true

    # returns true if one of the prefixes matches.
    "hello".start_with?("heaven", "hell")     #=> true
    "hello".start_with?("heaven", "paradise") #=> false

    static VALUE
    rb_str_start_with(int argc, VALUE *argv, VALUE str)
    {
        int i;

        for (i=0; i<argc; i++) {
            VALUE tmp = argv[i];
            if (RB_TYPE_P(tmp, T_REGEXP)) {
                if (rb_reg_start_with_p(tmp, str))
                    return Qtrue;
            }
            else {
                StringValue(tmp);
                rb_enc_check(str, tmp);
                if (RSTRING_LEN(str) < RSTRING_LEN(tmp)) continue;
                if (memcmp(RSTRING_PTR(str), RSTRING_PTR(tmp), RSTRING_LEN(tmp)) == 0)
                    return Qtrue;
            }
        }
        return Qfalse;
    }

strip → new_str click to toggle source

Returns a copy of the receiver with leading and trailing whitespace removed.

Whitespace is defined as any of the following characters: null, horizontal tab, line feed, vertical tab, form feed, carriage return, space.

    "    hello    ".strip   #=> "hello"
    "\tgoodbye\r\n".strip   #=> "goodbye"
    "\x00\t\n\v\f\r ".strip #=> ""
    "hello".strip           #=> "hello"

    static VALUE
    rb_str_strip(VALUE str)
    {
        char *start;
        long olen, loffset, roffset;
        rb_encoding *enc = STR_ENC_GET(str);

        RSTRING_GETMEM(str, start, olen);
        loffset = lstrip_offset(str, start, start+olen, enc);
        roffset = rstrip_offset(str, start+loffset, start+olen, enc);

        if (loffset <= 0 && roffset <= 0) return str_duplicate(rb_cString, str);
        return rb_str_subseq(str, loffset, olen-loffset-roffset);
    }

strip! → self or nil click to toggle source

Removes leading and trailing whitespace from the receiver. Returns the altered receiver, or `nil` if there was no change.

Refer to `String#strip` for the definition of whitespace.

    "  hello  ".strip!  #=> "hello"
    "hello".strip!      #=> nil

    static VALUE
    rb_str_strip_bang(VALUE str)
    {
        char *start;
        long olen, loffset, roffset;
        rb_encoding *enc;

        str_modify_keep_cr(str);
        enc = STR_ENC_GET(str);
        RSTRING_GETMEM(str, start, olen);
        loffset = lstrip_offset(str, start, start+olen, enc);
        roffset = rstrip_offset(str, start+loffset, start+olen, enc);

        if (loffset > 0 || roffset > 0) {
            long len = olen-roffset;
            if (loffset > 0) {
                len -= loffset;
                memmove(start, start + loffset, len);
            }
            STR_SET_LEN(str, len);
    #if !SHARABLE_MIDDLE_SUBSTRING
            TERM_FILL(start+len, rb_enc_mbminlen(enc));
    #endif
            return str;
        }
        return Qnil;
    }

sub(pattern, replacement) → new_str click to toggle source
sub(pattern, hash) → new_str
sub(pattern) {|match| block } → new_str

Returns a copy of `str` with the first occurrence of `pattern` replaced by the second argument. The `pattern` is typically a `Regexp`; if given as a `String`, any regular expression metacharacters it contains will be interpreted literally, e.g. `\d` will match a backslash followed by 'd', instead of a digit.

If `replacement` is a `String` it will be substituted for the matched text. It may contain back-references to the pattern's capture groups of the form `\d`, where d is a group number, or `\k<n>`, where n is a group name. Similarly, `\&`, `\'`, `\``, and `+` correspond to special variables, `$&`, `$'`, `$``, and `$+`, respectively. (See regexp.rdoc for details.) `\0` is the same as `\&`. `\\` is interpreted as an escape, i.e., a single backslash. Note that, within `replacement` the special match variables, such as `$&`, will not refer to the current match.

If the second argument is a `Hash`, and the matched text is one of its keys, the corresponding value is the replacement string.

In the block form, the current match string is passed in as a parameter, and variables such as `$1`, `$2`, `$``, `$&`, and `$'` will be set appropriately. (See regexp.rdoc for details.) The value returned by the block will be substituted for the match on each call.

    "hello".sub(/[aeiou]/, '*')                  #=> "h*llo"
    "hello".sub(/([aeiou])/, '<\1>')             #=> "h<e>llo"
    "hello".sub(/./) {|s| s.ord.to_s + ' ' }     #=> "104 ello"
    "hello".sub(/(?<foo>[aeiou])/, '*\k<foo>*')  #=> "h*e*llo"
    'Is SHELL your preferred shell?'.sub(/[[:upper:]]{2,}/, ENV)
     #=> "Is /bin/bash your preferred shell?"

Note that a string literal consumes backslashes. (See syntax/literals.rdoc for details about string literals.) Back-references are typically preceded by an additional backslash. For example, if you want to write a back-reference `\&` in `replacement` with a double-quoted string literal, you need to write: `"..\\&.."`. If you want to write a non-back-reference string `\&` in `replacement`, you need first to escape the backslash to prevent this method from interpreting it as a back-reference, and then you need to escape the backslashes again to prevent a string literal from consuming them: `"..\\\\&.."`. You may want to use the block form to avoid a lot of backslashes.

    static VALUE
    rb_str_sub(int argc, VALUE *argv, VALUE str)
    {
        str = str_duplicate(rb_cString, str);
        rb_str_sub_bang(argc, argv, str);
        return str;
    }

sub!(pattern, replacement) → str or nil click to toggle source
sub!(pattern) {|match| block } → str or nil

Performs the same substitution as `String#sub` in-place.

Returns `str` if a substitution was performed or `nil` if no substitution was performed.

    static VALUE
    rb_str_sub_bang(int argc, VALUE *argv, VALUE str)
    {
        VALUE pat, repl, hash = Qnil;
        int iter = 0;
        long plen;
        int min_arity = rb_block_given_p() ? 1 : 2;
        long beg;

        rb_check_arity(argc, min_arity, 2);
        if (argc == 1) {
            iter = 1;
        }
        else {
            repl = argv[1];
            hash = rb_check_hash_type(argv[1]);
            if (NIL_P(hash)) {
                StringValue(repl);
            }
        }

        pat = get_pat_quoted(argv[0], 1);

        str_modifiable(str);
        beg = rb_pat_search(pat, str, 0, 1);
        if (beg >= 0) {
            rb_encoding *enc;
            int cr = ENC_CODERANGE(str);
            long beg0, end0;
            VALUE match, match0 = Qnil;
            struct re_registers *regs;
            char *p, *rp;
            long len, rlen;

            match = rb_backref_get();
            regs = RMATCH_REGS(match);
            if (RB_TYPE_P(pat, T_STRING)) {
                beg0 = beg;
                end0 = beg0 + RSTRING_LEN(pat);
                match0 = pat;
            }
            else {
                beg0 = BEG(0);
                end0 = END(0);
                if (iter) match0 = rb_reg_nth_match(0, match);
            }

            if (iter || !NIL_P(hash)) {
                p = RSTRING_PTR(str); len = RSTRING_LEN(str);

                if (iter) {
                    repl = rb_obj_as_string(rb_yield(match0));
                }
                else {
                    repl = rb_hash_aref(hash, rb_str_subseq(str, beg0, end0 - beg0));
                    repl = rb_obj_as_string(repl);
                }
                str_mod_check(str, p, len);
                rb_check_frozen(str);
            }
            else {
                repl = rb_reg_regsub(repl, str, regs, RB_TYPE_P(pat, T_STRING) ? Qnil : pat);
            }

            enc = rb_enc_compatible(str, repl);
            if (!enc) {
                rb_encoding *str_enc = STR_ENC_GET(str);
                p = RSTRING_PTR(str); len = RSTRING_LEN(str);
                if (coderange_scan(p, beg0, str_enc) != ENC_CODERANGE_7BIT ||
                    coderange_scan(p+end0, len-end0, str_enc) != ENC_CODERANGE_7BIT) {
                    rb_raise(rb_eEncCompatError, "incompatible character encodings: %s and %s",
                             rb_enc_name(str_enc),
                             rb_enc_name(STR_ENC_GET(repl)));
                }
                enc = STR_ENC_GET(repl);
            }
            rb_str_modify(str);
            rb_enc_associate(str, enc);
            if (ENC_CODERANGE_UNKNOWN < cr && cr < ENC_CODERANGE_BROKEN) {
                int cr2 = ENC_CODERANGE(repl);
                if (cr2 == ENC_CODERANGE_BROKEN ||
                    (cr == ENC_CODERANGE_VALID && cr2 == ENC_CODERANGE_7BIT))
                    cr = ENC_CODERANGE_UNKNOWN;
                else
                    cr = cr2;
            }
            plen = end0 - beg0;
            rlen = RSTRING_LEN(repl);
            len = RSTRING_LEN(str);
            if (rlen > plen) {
                RESIZE_CAPA(str, len + rlen - plen);
            }
            p = RSTRING_PTR(str);
            if (rlen != plen) {
                memmove(p + beg0 + rlen, p + beg0 + plen, len - beg0 - plen);
            }
            rp = RSTRING_PTR(repl);
            memmove(p + beg0, rp, rlen);
            len += rlen - plen;
            STR_SET_LEN(str, len);
            TERM_FILL(&RSTRING_PTR(str)[len], TERM_LEN(str));
            ENC_CODERANGE_SET(str, cr);

            return str;
        }
        return Qnil;
    }

succ → new_str click to toggle source

Returns the successor to `self`. The successor is calculated by incrementing characters.

The first character to be incremented is the rightmost alphanumeric: or, if no alphanumerics, the rightmost character:

    'THX1138'.succ # => "THX1139"
    '<<koala>>'.succ # => "<<koalb>>"
    '***'.succ # => '**+'

The successor to a digit is another digit, “carrying” to the next-left character for a “rollover” from 9 to 0, and prepending another digit if necessary:

    '00'.succ # => "01"
    '09'.succ # => "10"
    '99'.succ # => "100"

The successor to a letter is another letter of the same case, carrying to the next-left character for a rollover, and prepending another same-case letter if necessary:

    'aa'.succ # => "ab"
    'az'.succ # => "ba"
    'zz'.succ # => "aaa"
    'AA'.succ # => "AB"
    'AZ'.succ # => "BA"
    'ZZ'.succ # => "AAA"

The successor to a non-alphanumeric character is the next character in the underlying character set's collating sequence, carrying to the next-left character for a rollover, and prepending another character if necessary:

    s = 0.chr * 3
    s # => "\x00\x00\x00"
    s.succ # => "\x00\x00\x01"
    s = 255.chr * 3
    s # => "\xFF\xFF\xFF"
    s.succ # => "\x01\x00\x00\x00"

Carrying can occur between and among mixtures of alphanumeric characters:

    s = 'zz99zz99'
    s.succ # => "aaa00aa00"
    s = '99zz99zz'
    s.succ # => "100aa00aa"

The successor to an empty String is a new empty String:

    ''.succ # => ""

`String#next` is an alias for `String#succ`.

    VALUE
    rb_str_succ(VALUE orig)
    {
        VALUE str;
        str = rb_str_new(RSTRING_PTR(orig), RSTRING_LEN(orig));
        rb_enc_cr_str_copy_for_substr(str, orig);
        return str_succ(str);
    }

Also aliased as: next
succ! → self click to toggle source

Equivalent to `String#succ`, but modifies `self` in place; returns `self`.

`String#next!` is an alias for `String#succ!`.

    static VALUE
    rb_str_succ_bang(VALUE str)
    {
        rb_str_modify(str);
        str_succ(str);
        return str;
    }

Also aliased as: next!
sum(n=16) → integer click to toggle source

Returns a basic n-bit checksum of the characters in str, where n is the optional `Integer` parameter, defaulting to 16. The result is simply the sum of the binary value of each byte in str modulo `2**n - 1`. This is not a particularly good checksum.

    static VALUE
    rb_str_sum(int argc, VALUE *argv, VALUE str)
    {
        int bits = 16;
        char *ptr, *p, *pend;
        long len;
        VALUE sum = INT2FIX(0);
        unsigned long sum0 = 0;

        if (rb_check_arity(argc, 0, 1) && (bits = NUM2INT(argv[0])) < 0) {
            bits = 0;
        }
        ptr = p = RSTRING_PTR(str);
        len = RSTRING_LEN(str);
        pend = p + len;

        while (p < pend) {
            if (FIXNUM_MAX - UCHAR_MAX < sum0) {
                sum = rb_funcall(sum, '+', 1, LONG2FIX(sum0));
                str_mod_check(str, ptr, len);
                sum0 = 0;
            }
            sum0 += (unsigned char)*p;
            p++;
        }

        if (bits == 0) {
            if (sum0) {
                sum = rb_funcall(sum, '+', 1, LONG2FIX(sum0));
            }
        }
        else {
            if (sum == INT2FIX(0)) {
                if (bits < (int)sizeof(long)*CHAR_BIT) {
                    sum0 &= (((unsigned long)1)<<bits)-1;
                }
                sum = LONG2FIX(sum0);
            }
            else {
                VALUE mod;

                if (sum0) {
                    sum = rb_funcall(sum, '+', 1, LONG2FIX(sum0));
                }

                mod = rb_funcall(INT2FIX(1), idLTLT, 1, INT2FIX(bits));
                mod = rb_funcall(mod, '-', 1, INT2FIX(1));
                sum = rb_funcall(sum, '&', 1, mod);
            }
        }
        return sum;
    }

swapcase → new_str click to toggle source
swapcase([options]) → new_str

Returns a copy of str with uppercase alphabetic characters converted to lowercase and lowercase characters converted to uppercase.

See `String#downcase` for meaning of `options` and use with different encodings.

    "Hello".swapcase          #=> "hELLO"
    "cYbEr_PuNk11".swapcase   #=> "CyBeR_pUnK11"

    static VALUE
    rb_str_swapcase(int argc, VALUE *argv, VALUE str)
    {
        rb_encoding *enc;
        OnigCaseFoldType flags = ONIGENC_CASE_UPCASE | ONIGENC_CASE_DOWNCASE;
        VALUE ret;

        flags = check_case_options(argc, argv, flags);
        enc = str_true_enc(str);
        if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return str_duplicate(rb_cString, str);
        if (flags&ONIGENC_CASE_ASCII_ONLY) {
            ret = rb_str_new(0, RSTRING_LEN(str));
            rb_str_ascii_casemap(str, ret, &flags, enc);
        }
        else {
            ret = rb_str_casemap(str, &flags, enc);
        }
        return ret;
    }

swapcase! → str or nil click to toggle source
swapcase!([options]) → str or nil

Equivalent to `String#swapcase`, but modifies the receiver in place, returning str, or `nil` if no changes were made.

See `String#downcase` for meaning of `options` and use with different encodings.

    static VALUE
    rb_str_swapcase_bang(int argc, VALUE *argv, VALUE str)
    {
        rb_encoding *enc;
        OnigCaseFoldType flags = ONIGENC_CASE_UPCASE | ONIGENC_CASE_DOWNCASE;

        flags = check_case_options(argc, argv, flags);
        str_modify_keep_cr(str);
        enc = str_true_enc(str);
        if (flags&ONIGENC_CASE_ASCII_ONLY)
            rb_str_ascii_casemap(str, str, &flags, enc);
        else
            str_shared_replace(str, rb_str_casemap(str, &flags, enc));

        if (ONIGENC_CASE_MODIFIED&flags) return str;
        return Qnil;
    }

to_c → complex click to toggle source

Returns a complex which denotes the string form. The parser ignores leading whitespaces and trailing garbage. Any digit sequences can be separated by an underscore. Returns zero for null or garbage string.

    '9'.to_c           #=> (9+0i)
    '2.5'.to_c         #=> (2.5+0i)
    '2.5/1'.to_c       #=> ((5/2)+0i)
    '-3/2'.to_c        #=> ((-3/2)+0i)
    '-i'.to_c          #=> (0-1i)
    '45i'.to_c         #=> (0+45i)
    '3-4i'.to_c        #=> (3-4i)
    '-4e2-4e-2i'.to_c  #=> (-400.0-0.04i)
    '-0.0-0.0i'.to_c   #=> (-0.0-0.0i)
    '1/2+3/4i'.to_c    #=> ((1/2)+(3/4)*i)
    'ruby'.to_c        #=> (0+0i)

See `Kernel`.Complex.

    static VALUE
    string_to_c(VALUE self)
    {
        char *s;
        VALUE num;

        rb_must_asciicompat(self);

        s = RSTRING_PTR(self);

        if (s && s[RSTRING_LEN(self)]) {
            rb_str_modify(self);
            s = RSTRING_PTR(self);
            s[RSTRING_LEN(self)] = '\0';
        }

        if (!s)
            s = (char *)"";

        (void)parse_comp(s, 0, &num);

        return num;
    }

to_d → bigdecimal click to toggle source

Returns the result of interpreting leading characters in `str` as a `BigDecimal`.

    require 'bigdecimal'
    require 'bigdecimal/util'

    "0.5".to_d             # => 0.5e0
    "123.45e1".to_d        # => 0.12345e4
    "45.67 degrees".to_d   # => 0.4567e2

See also `BigDecimal::new`.

    # File ext/bigdecimal/lib/bigdecimal/util.rb, line 68
    def to_d
      BigDecimal.interpret_loosely(self)
    end

to_f → float click to toggle source

Returns the result of interpreting leading characters in str as a floating point number. Extraneous characters past the end of a valid number are ignored. If there is not a valid number at the start of str, `0.0` is returned. This method never raises an exception.

    "123.45e1".to_f        #=> 1234.5
    "45.67 degrees".to_f   #=> 45.67
    "thx1138".to_f         #=> 0.0

    static VALUE
    rb_str_to_f(VALUE str)
    {
        return DBL2NUM(rb_str_to_dbl(str, FALSE));
    }

to_i(base=10) → integer click to toggle source

Returns the result of interpreting leading characters in str as an integer base base (between 2 and 36). Extraneous characters past the end of a valid number are ignored. If there is not a valid number at the start of str, `0` is returned. This method never raises an exception when base is valid.

    "12345".to_i             #=> 12345
    "99 red balloons".to_i   #=> 99
    "0a".to_i                #=> 0
    "0a".to_i(16)            #=> 10
    "hello".to_i             #=> 0
    "1100101".to_i(2)        #=> 101
    "1100101".to_i(8)        #=> 294977
    "1100101".to_i(10)       #=> 1100101
    "1100101".to_i(16)       #=> 17826049

    static VALUE
    rb_str_to_i(int argc, VALUE *argv, VALUE str)
    {
        int base = 10;

        if (rb_check_arity(argc, 0, 1) && (base = NUM2INT(argv[0])) < 0) {
            rb_raise(rb_eArgError, "invalid radix %d", base);
        }
        return rb_str_to_inum(str, base, FALSE);
    }

to_r → rational click to toggle source

Returns the result of interpreting leading characters in `str` as a rational. Leading whitespace and extraneous characters past the end of a valid number are ignored. Digit sequences can be separated by an underscore. If there is not a valid number at the start of `str`, zero is returned. This method never raises an exception.

    '  2  '.to_r       #=> (2/1)
    '300/2'.to_r       #=> (150/1)
    '-9.2'.to_r        #=> (-46/5)
    '-9.2e2'.to_r      #=> (-920/1)
    '1_234_567'.to_r   #=> (1234567/1)
    '21 June 09'.to_r  #=> (21/1)
    '21/06/09'.to_r    #=> (7/2)
    'BWV 1079'.to_r    #=> (0/1)

NOTE: “0.3”.to_r isn't the same as 0.3.to_r. The former is equivalent to “3/10”.to_r, but the latter isn't so.

    "0.3".to_r == 3/10r  #=> true
    0.3.to_r   == 3/10r  #=> false

See also Kernel#Rational.

    static VALUE
    string_to_r(VALUE self)
    {
        VALUE num;

        rb_must_asciicompat(self);

        num = parse_rat(RSTRING_PTR(self), RSTRING_END(self), 0, TRUE);

        if (RB_FLOAT_TYPE_P(num) && !FLOAT_ZERO_P(num))
            rb_raise(rb_eFloatDomainError, "Infinity");
        return num;
    }

to_s → str click to toggle source

Returns `self`.

If called on a subclass of `String`, converts the receiver to a `String` object.

    static VALUE
    rb_str_to_s(VALUE str)
    {
        if (rb_obj_class(str) != rb_cString) {
            return str_duplicate(rb_cString, str);
        }
        return str;
    }

Also aliased as: to_str

Returns `self`.

If called on a subclass of `String`, converts the receiver to a `String` object.

Alias for: to_s
to_sym → symbol

Returns the `Symbol` corresponding to str, creating the symbol if it did not previously exist. See `Symbol#id2name`.

    "Koala".intern         #=> :Koala
    s = 'cat'.to_sym       #=> :cat
    s == :cat              #=> true
    s = '@cat'.to_sym      #=> :@cat
    s == :@cat             #=> true

This can also be used to create symbols that cannot be represented using the `:xxx` notation.

    'cat and dog'.to_sym   #=> :"cat and dog"

Alias for: intern
String#toeuc → string click to toggle source

Convert `self` to EUC-JP

    # File ext/nkf/lib/kconv.rb, line 224
    def toeuc; Kconv.toeuc(self) end

String#tojis → string click to toggle source

Convert `self` to ISO-2022-JP

    # File ext/nkf/lib/kconv.rb, line 218
    def tojis; Kconv.tojis(self) end

String#tolocale → string click to toggle source

Convert `self` to locale encoding

    # File ext/nkf/lib/kconv.rb, line 254
    def tolocale; Kconv.tolocale(self) end

String#tosjis → string click to toggle source

Convert `self` to Shift_JIS

    # File ext/nkf/lib/kconv.rb, line 230
    def tosjis; Kconv.tosjis(self) end

String#toutf16 → string click to toggle source

Convert `self` to UTF-16

    # File ext/nkf/lib/kconv.rb, line 242
    def toutf16; Kconv.toutf16(self) end

String#toutf32 → string click to toggle source

Convert `self` to UTF-32

    # File ext/nkf/lib/kconv.rb, line 248
    def toutf32; Kconv.toutf32(self) end

String#toutf8 → string click to toggle source

Convert `self` to UTF-8

    # File ext/nkf/lib/kconv.rb, line 236
    def toutf8; Kconv.toutf8(self) end

tr(from_str, to_str) → new_str click to toggle source

Returns a copy of `str` with the characters in `from_str` replaced by the corresponding characters in `to_str`. If `to_str` is shorter than `from_str`, it is padded with its last character in order to maintain the correspondence.

    "hello".tr('el', 'ip')      #=> "hippo"
    "hello".tr('aeiou', '*')    #=> "h*ll*"
    "hello".tr('aeiou', 'AA*')  #=> "hAll*"

Both strings may use the `c1-c2` notation to denote ranges of characters, and `from_str` may start with a `^`, which denotes all characters except those listed.

    "hello".tr('a-y', 'b-z')    #=> "ifmmp"
    "hello".tr('^aeiou', '*')   #=> "*e**o"

The backslash character `\` can be used to escape `^` or `-` and is otherwise ignored unless it appears at the end of a range or the end of the `from_str` or `to_str`:

    "hello^world".tr("\\^aeiou", "*") #=> "h*ll**w*rld"
    "hello-world".tr("a\\-eo", "*")   #=> "h*ll**w*rld"

    "hello\r\nworld".tr("\r", "")   #=> "hello\nworld"
    "hello\r\nworld".tr("\\r", "")  #=> "hello\r\nwold"
    "hello\r\nworld".tr("\\\r", "") #=> "hello\nworld"

    "X['\\b']".tr("X\\", "")   #=> "['b']"
    "X['\\b']".tr("X-\\]", "") #=> "'b'"

    static VALUE
    rb_str_tr(VALUE str, VALUE src, VALUE repl)
    {
        str = str_duplicate(rb_cString, str);
        tr_trans(str, src, repl, 0);
        return str;
    }

tr!(from_str, to_str) → str or nil click to toggle source

Translates str in place, using the same rules as `String#tr`. Returns str, or `nil` if no changes were made.

    static VALUE
    rb_str_tr_bang(VALUE str, VALUE src, VALUE repl)
    {
        return tr_trans(str, src, repl, 0);
    }

tr_s(from_str, to_str) → new_str click to toggle source

Processes a copy of str as described under `String#tr`, then removes duplicate characters in regions that were affected by the translation.

    "hello".tr_s('l', 'r')     #=> "hero"
    "hello".tr_s('el', '*')    #=> "h*o"
    "hello".tr_s('el', 'hx')   #=> "hhxo"

    static VALUE
    rb_str_tr_s(VALUE str, VALUE src, VALUE repl)
    {
        str = str_duplicate(rb_cString, str);
        tr_trans(str, src, repl, 1);
        return str;
    }

tr_s!(from_str, to_str) → str or nil click to toggle source

Performs `String#tr_s` processing on str in place, returning str, or `nil` if no changes were made.

    static VALUE
    rb_str_tr_s_bang(VALUE str, VALUE src, VALUE repl)
    {
        return tr_trans(str, src, repl, 1);
    }

undump → new_str click to toggle source

Returns an unescaped version of the string. This does the inverse of `String#dump`.

    "\"hello \\n ''\"".undump #=> "hello \n ''"

    static VALUE
    str_undump(VALUE str)
    {
        const char *s = RSTRING_PTR(str);
        const char *s_end = RSTRING_END(str);
        rb_encoding *enc = rb_enc_get(str);
        VALUE undumped = rb_enc_str_new(s, 0L, enc);
        bool utf8 = false;
        bool binary = false;
        int w;

        rb_must_asciicompat(str);
        if (rb_str_is_ascii_only_p(str) == Qfalse) {
            rb_raise(rb_eRuntimeError, "non-ASCII character detected");
        }
        if (!str_null_check(str, &w)) {
            rb_raise(rb_eRuntimeError, "string contains null byte");
        }
        if (RSTRING_LEN(str) < 2) goto invalid_format;
        if (*s != '"') goto invalid_format;

        /* strip '"' at the start */
        s++;

        for (;;) {
            if (s >= s_end) {
                rb_raise(rb_eRuntimeError, "unterminated dumped string");
            }

            if (*s == '"') {
                /* epilogue */
                s++;
                if (s == s_end) {
                    /* ascii compatible dumped string */
                    break;
                }
                else {
                    static const char force_encoding_suffix[] = ".force_encoding(\""; /* "\")" */
                    static const char dup_suffix[] = ".dup";
                    const char *encname;
                    int encidx;
                    ptrdiff_t size;

                    /* check separately for strings dumped by older versions */
                    size = sizeof(dup_suffix) - 1;
                    if (s_end - s > size && memcmp(s, dup_suffix, size) == 0) s += size;

                    size = sizeof(force_encoding_suffix) - 1;
                    if (s_end - s <= size) goto invalid_format;
                    if (memcmp(s, force_encoding_suffix, size) != 0) goto invalid_format;
                    s += size;

                    if (utf8) {
                        rb_raise(rb_eRuntimeError, "dumped string contained Unicode escape but used force_encoding");
                    }

                    encname = s;
                    s = memchr(s, '"', s_end-s);
                    size = s - encname;
                    if (!s) goto invalid_format;
                    if (s_end - s != 2) goto invalid_format;
                    if (s[0] != '"' || s[1] != ')') goto invalid_format;

                    encidx = rb_enc_find_index2(encname, (long)size);
                    if (encidx < 0) {
                        rb_raise(rb_eRuntimeError, "dumped string has unknown encoding name");
                    }
                    rb_enc_associate_index(undumped, encidx);
                }
                break;
            }

            if (*s == '\\') {
                s++;
                if (s >= s_end) {
                    rb_raise(rb_eRuntimeError, "invalid escape");
                }
                undump_after_backslash(undumped, &s, s_end, &enc, &utf8, &binary);
            }
            else {
                rb_str_cat(undumped, s++, 1);
            }
        }

        return undumped;
    invalid_format:
        rb_raise(rb_eRuntimeError, "invalid dumped string; not wrapped with '\"' nor '\"...\".force_encoding(\"...\")' form");
    }

unicode_normalize(form=:nfc) click to toggle source

Unicode Normalization—Returns a normalized form of `str`, using Unicode normalizations NFC, NFD, NFKC, or NFKD. The normalization form used is determined by `form`, which can be any of the four values `:nfc`, `:nfd`, `:nfkc`, or `:nfkd`. The default is `:nfc`.

If the string is not in a Unicode `Encoding`, then an `Exception` is raised. In this context, 'Unicode Encoding' means any of UTF-8, UTF-16BE/LE, and UTF-32BE/LE, as well as GB18030, UCS_2BE, and UCS_4BE. Anything other than UTF-8 is implemented by converting to UTF-8, which makes it slower than UTF-8.

    "a\u0300".unicode_normalize        #=> "\u00E0"
    "a\u0300".unicode_normalize(:nfc)  #=> "\u00E0"
    "\u00E0".unicode_normalize(:nfd)   #=> "a\u0300"
    "\xE0".force_encoding('ISO-8859-1').unicode_normalize(:nfd)
                                       #=> Encoding::CompatibilityError raised

    static VALUE
    rb_str_unicode_normalize(int argc, VALUE *argv, VALUE str)
    {
        return unicode_normalize_common(argc, argv, str, id_normalize);
    }

unicode_normalize!(form=:nfc) click to toggle source

Destructive version of `String#unicode_normalize`, doing Unicode normalization in place.

    static VALUE
    rb_str_unicode_normalize_bang(int argc, VALUE *argv, VALUE str)
    {
        return rb_str_replace(str, unicode_normalize_common(argc, argv, str, id_normalize));
    }

unicode_normalized?(form=:nfc) click to toggle source

Checks whether `str` is in Unicode normalization form `form`, which can be any of the four values `:nfc`, `:nfd`, `:nfkc`, or `:nfkd`. The default is `:nfc`.

If the string is not in a Unicode `Encoding`, then an `Exception` is raised. For details, see `String#unicode_normalize`.

    "a\u0300".unicode_normalized?        #=> false
    "a\u0300".unicode_normalized?(:nfd)  #=> true
    "\u00E0".unicode_normalized?         #=> true
    "\u00E0".unicode_normalized?(:nfd)   #=> false
    "\xE0".force_encoding('ISO-8859-1').unicode_normalized?
                                         #=> Encoding::CompatibilityError raised

    static VALUE
    rb_str_unicode_normalized_p(int argc, VALUE *argv, VALUE str)
    {
        return unicode_normalize_common(argc, argv, str, id_normalized_p);
    }

unpack(format) → anArray click to toggle source

Decodes str (which may contain binary data) according to the format string, returning an array of each value extracted. The format string consists of a sequence of single-character directives, summarized in the table at the end of this entry. Each directive may be followed by a number, indicating the number of times to repeat with this directive. An asterisk (“`*`'') will use up all remaining elements. The directives `sSiIlL` may each be followed by an underscore (“`_`'') or exclamation mark (“`!`'') to use the underlying platform's native size for the specified type; otherwise, it uses a platform-independent consistent size. Spaces are ignored in the format string. See also `String#unpack1`, `Array#pack`.

    "abc \0\0abc \0\0".unpack('A6Z6')   #=> ["abc", "abc "]
    "abc \0\0".unpack('a3a3')           #=> ["abc", " \000\000"]
    "abc \0abc \0".unpack('Z*Z*')       #=> ["abc ", "abc "]
    "aa".unpack('b8B8')                 #=> ["10000110", "01100001"]
    "aaa".unpack('h2H2c')               #=> ["16", "61", 97]
    "\xfe\xff\xfe\xff".unpack('sS')     #=> [-2, 65534]
    "now=20is".unpack('M*')             #=> ["now is"]
    "whole".unpack('xax2aX2aX1aX2a')    #=> ["h", "e", "l", "l", "o"]

This table summarizes the various formats and the Ruby classes returned by each.

    Integer       |         |
    Directive     | Returns | Meaning
    ------------------------------------------------------------------
    C             | Integer | 8-bit unsigned (unsigned char)
    S             | Integer | 16-bit unsigned, native endian (uint16_t)
    L             | Integer | 32-bit unsigned, native endian (uint32_t)
    Q             | Integer | 64-bit unsigned, native endian (uint64_t)
    J             | Integer | pointer width unsigned, native endian (uintptr_t)
                  |         |
    c             | Integer | 8-bit signed (signed char)
    s             | Integer | 16-bit signed, native endian (int16_t)
    l             | Integer | 32-bit signed, native endian (int32_t)
    q             | Integer | 64-bit signed, native endian (int64_t)
    j             | Integer | pointer width signed, native endian (intptr_t)
                  |         |
    S_ S!         | Integer | unsigned short, native endian
    I I_ I!       | Integer | unsigned int, native endian
    L_ L!         | Integer | unsigned long, native endian
    Q_ Q!         | Integer | unsigned long long, native endian (ArgumentError
                  |         | if the platform has no long long type.)
    J!            | Integer | uintptr_t, native endian (same with J)
                  |         |
    s_ s!         | Integer | signed short, native endian
    i i_ i!       | Integer | signed int, native endian
    l_ l!         | Integer | signed long, native endian
    q_ q!         | Integer | signed long long, native endian (ArgumentError
                  |         | if the platform has no long long type.)
    j!            | Integer | intptr_t, native endian (same with j)
                  |         |
    S> s> S!> s!> | Integer | same as the directives without ">" except
    L> l> L!> l!> |         | big endian
    I!> i!>       |         |
    Q> q> Q!> q!> |         | "S>" is same as "n"
    J> j> J!> j!> |         | "L>" is same as "N"
                  |         |
    S< s< S!< s!< | Integer | same as the directives without "<" except
    L< l< L!< l!< |         | little endian
    I!< i!<       |         |
    Q< q< Q!< q!< |         | "S<" is same as "v"
    J< j< J!< j!< |         | "L<" is same as "V"
                  |         |
    n             | Integer | 16-bit unsigned, network (big-endian) byte order
    N             | Integer | 32-bit unsigned, network (big-endian) byte order
    v             | Integer | 16-bit unsigned, VAX (little-endian) byte order
    V             | Integer | 32-bit unsigned, VAX (little-endian) byte order
                  |         |
    U             | Integer | UTF-8 character
    w             | Integer | BER-compressed integer (see Array#pack)

    Float        |         |
    Directive    | Returns | Meaning
    -----------------------------------------------------------------
    D d          | Float   | double-precision, native format
    F f          | Float   | single-precision, native format
    E            | Float   | double-precision, little-endian byte order
    e            | Float   | single-precision, little-endian byte order
    G            | Float   | double-precision, network (big-endian) byte order
    g            | Float   | single-precision, network (big-endian) byte order

    String       |         |
    Directive    | Returns | Meaning
    -----------------------------------------------------------------
    A            | String  | arbitrary binary string (remove trailing nulls and ASCII spaces)
    a            | String  | arbitrary binary string
    Z            | String  | null-terminated string
    B            | String  | bit string (MSB first)
    b            | String  | bit string (LSB first)
    H            | String  | hex string (high nibble first)
    h            | String  | hex string (low nibble first)
    u            | String  | UU-encoded string
    M            | String  | quoted-printable, MIME encoding (see RFC2045)
    m            | String  | base64 encoded string (RFC 2045) (default)
                 |         | base64 encoded string (RFC 4648) if followed by 0
    P            | String  | pointer to a structure (fixed-length string)
    p            | String  | pointer to a null-terminated string

    Misc.        |         |
    Directive    | Returns | Meaning
    -----------------------------------------------------------------
    @            | ---     | skip to the offset given by the length argument
    X            | ---     | skip backward one byte
    x            | ---     | skip forward one byte

HISTORY

- J, J! j, and j! are available since Ruby 2.3.

- Q_, Q!, q_, and q! are available since Ruby 2.1.

- I!<, i!<, I!>, and i!> are available since Ruby 1.9.3.

    # File pack.rb, line 256
    def unpack(fmt)
      Primitive.pack_unpack(fmt)
    end

unpack1(format) → obj click to toggle source

Decodes str (which may contain binary data) according to the format string, returning the first value extracted. See also `String#unpack`, `Array#pack`.

Contrast with `String#unpack`:

    "abc \0\0abc \0\0".unpack('A6Z6')   #=> ["abc", "abc "]
    "abc \0\0abc \0\0".unpack1('A6Z6')  #=> "abc"

In that case data would be lost but often it's the case that the array only holds one value, especially when unpacking binary data. For instance:

“xffx00x00x00”.unpack(“l”) #=> [255] “xffx00x00x00”.unpack1(“l”) #=> 255

Thus unpack1 is convenient, makes clear the intention and signals the expected return value to those reading the code.

    # File pack.rb, line 280
    def unpack1(fmt)
      Primitive.pack_unpack1(fmt)
    end

upcase → new_str click to toggle source
upcase([options]) → new_str

Returns a copy of str with all lowercase letters replaced with their uppercase counterparts.

See `String#downcase` for meaning of `options` and use with different encodings.

    "hEllO".upcase   #=> "HELLO"

    static VALUE
    rb_str_upcase(int argc, VALUE *argv, VALUE str)
    {
        rb_encoding *enc;
        OnigCaseFoldType flags = ONIGENC_CASE_UPCASE;
        VALUE ret;

        flags = check_case_options(argc, argv, flags);
        enc = str_true_enc(str);
        if (case_option_single_p(flags, enc, str)) {
            ret = rb_str_new(RSTRING_PTR(str), RSTRING_LEN(str));
            str_enc_copy(ret, str);
            upcase_single(ret);
        }
        else if (flags&ONIGENC_CASE_ASCII_ONLY) {
            ret = rb_str_new(0, RSTRING_LEN(str));
            rb_str_ascii_casemap(str, ret, &flags, enc);
        }
        else {
            ret = rb_str_casemap(str, &flags, enc);
        }

        return ret;
    }

upcase! → str or nil click to toggle source
upcase!([options]) → str or nil

Upcases the contents of str, returning `nil` if no changes were made.

See `String#downcase` for meaning of `options` and use with different encodings.

    static VALUE
    rb_str_upcase_bang(int argc, VALUE *argv, VALUE str)
    {
        rb_encoding *enc;
        OnigCaseFoldType flags = ONIGENC_CASE_UPCASE;

        flags = check_case_options(argc, argv, flags);
        str_modify_keep_cr(str);
        enc = str_true_enc(str);
        if (case_option_single_p(flags, enc, str)) {
            if (upcase_single(str))
                flags |= ONIGENC_CASE_MODIFIED;
        }
        else if (flags&ONIGENC_CASE_ASCII_ONLY)
            rb_str_ascii_casemap(str, str, &flags, enc);
        else
            str_shared_replace(str, rb_str_casemap(str, &flags, enc));

        if (ONIGENC_CASE_MODIFIED&flags) return str;
        return Qnil;
    }

upto(other_string, exclusive = false) {|string| ... } → self click to toggle source
upto(other_string, exclusive = false) → new_enumerator

With a block given, calls the block with each String value returned by successive calls to `String#succ`; the first value is `self`, the next is `self.succ`, and so on; the sequence terminates when value `other_string` is reached; returns `self`:

    'a8'.upto('b6') {|s| print s, ' ' } # => "a8"

Output:

    a8 a9 b0 b1 b2 b3 b4 b5 b6

If argument `exclusive` is given as a truthy object, the last value is omitted:

    'a8'.upto('b6', true) {|s| print s, ' ' } # => "a8"

Output:

    a8 a9 b0 b1 b2 b3 b4 b5

If `other_string` would not be reached, does not call the block:

    '25'.upto('5') {|s| fail s }
    'aa'.upto('a') {|s| fail s }

With no block given, returns a new Enumerator:

    'a8'.upto('b6') # => #<Enumerator: "a8":upto("b6")>

    static VALUE
    rb_str_upto(int argc, VALUE *argv, VALUE beg)
    {
        VALUE end, exclusive;

        rb_scan_args(argc, argv, "11", &end, &exclusive);
        RETURN_ENUMERATOR(beg, argc, argv);
        return rb_str_upto_each(beg, end, RTEST(exclusive), str_upto_i, Qnil);
    }

valid_encoding? → true or false click to toggle source

Returns true for a string which is encoded correctly.

    "\xc2\xa1".force_encoding("UTF-8").valid_encoding?  #=> true
    "\xc2".force_encoding("UTF-8").valid_encoding?      #=> false
    "\x80".force_encoding("UTF-8").valid_encoding?      #=> false

    static VALUE
    rb_str_valid_encoding_p(VALUE str)
    {
        int cr = rb_enc_str_coderange(str);

        return cr == ENC_CODERANGE_BROKEN ? Qfalse : Qtrue;
    }