instance method · added in Ruby 3.4

MatchData#bytebegin

(::MatchData::capture backref) -> ::Integer?

bytebegin(n) → integer

bytebegin(name) → integer

static VALUE
match_bytebegin(VALUE match, VALUE n)
{
    int i = match_backref_number(match, n);
    struct re_registers *regs = RMATCH_REGS(match);

    match_check(match);
    backref_number_check(regs, i);

    if (BEG(i) < 0)
        return Qnil;
    return LONG2NUM(BEG(i));
}

Returns the offset (in bytes) of the beginning of the specified match.

When non-negative integer argument n is given, returns the offset of the beginning of the nth match:

Example

m = /(.)(.)(\d+)(\d)/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m[0]       # => "HX1138"
m.bytebegin(0) # => 1
m[3]       # => "113"
m.bytebegin(3) # => 3

m = /(т)(е)(с)/.match('тест')
# => #<MatchData "тес" 1:"т" 2:"е" 3:"с">
m[0]       # => "тес"
m.bytebegin(0) # => 0
m[3]       # => "с"
m.bytebegin(3) # => 4

When string or symbol argument name is given, returns the offset of the beginning for the named match:

Example

m = /(?<foo>.)(.)(?<bar>.)/.match("hoge")
# => #<MatchData "hog" foo:"h" bar:"g">
m[:foo]        # => "h"
m.bytebegin('foo') # => 0
m[:bar]        # => "g"
m.bytebegin(:bar)  # => 2

Ruby version changes

3.4
- MatchData#bytebegin and MatchData#byteend have been added. [Feature #20576]

See also #begin #byteend #[] #byteoffset also in 4.1 · 3.4

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