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instance method · added in Ruby 4.1

MatchData#integer_at

integer_at(index, base = 10) → integer or nil

integer_at(name, base = 10) → integer or nil

static VALUE
match_integer_at(int argc, VALUE *argv, VALUE match)
{
    match_check(match);

    int base = 10;
    VALUE idx;
    int nth;

    argc = rb_check_arity(argc, 1, 2);
    if (FIXNUM_P(idx = argv[0])) {
        nth = NUM2INT(idx);
    }
    else if ((nth = namev_to_backref_number(match, idx)) < 0) {
        name_to_backref_error(idx);
    }

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

    if (nth >= RMATCH_NREGS(match)) return Qnil;
    if (nth < 0 && (nth += RMATCH_NREGS(match)) <= 0) return Qnil;

    rb_len_t start = RMATCH_BEG(match, nth), end = RMATCH_END(match, nth);
    if (start < 0) return Qnil;
    RUBY_ASSERT(start <= end, "%"PRIdLEN" > %"PRIdLEN, start, end);

    VALUE str = RMATCH(match)->str;
    RUBY_ASSERT(end <= RSTRING_LEN(str), "%"PRIdLEN" > %"PRIdLEN, end, RSTRING_LEN(str));

    char *endp;
    return rb_int_parse_cstr(RSTRING_PTR(str) + start, end - start, &endp, NULL,
                             base, RB_INT_PARSE_DEFAULT);
}

Converts the matched substring to integer and return the result. +$~.integer_at(N)+ is equivalent to +$N&.to_i+.

Example

m = /(\d+{4})(\d+{2})(\d+{2})/.match("20260308")
# => #<MatchData "20260308" 1:"2026" 2:"03" 3:"08">
m.integer_at(0)     # => 20260308
m.integer_at(1)     # => 2026
m.integer_at(2)     # => 3
m.integer_at(3)     # => 8

m = /(?<y>\d+{4})(?<m>\d+{2})(?<d>\d+{2})/.match("20260308")
m.integer_at("y")   # => 2026
m.integer_at("m")   # => 3
m.integer_at("d")   # => 8

If the substring does not match, returns nil.

Example

re = /(\d+)?/
re.match("123").integer_at(1) #=> 123
re.match("abc").integer_at(1) #=> nil

The string is converted in decimal by default.

Example

/\d+/.match("011").integer_at(0)     #=> 10
/\d+/.match("011").integer_at(0, 12) #=> 13
/\d+/.match("011").integer_at(0, 0)  #=> 9

Ruby version changes

4.1
- MatchData#integer_at is added. It converts the matched substring to integer and return the result. [Feature #21932]