End of Life Ruby 3.1 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →

instance method

String#sub

sub(pattern, replacement) → new_string

sub(pattern) {|match| ... } → new_string

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;
}

Returns a copy of self with only the first occurrence (not all occurrences) of the given pattern replaced.

See Substitution Methods.

Ruby version changes

3.0
- The following methods now return or yield String instances instead of subclass instances when called on subclass instances: [Bug #10845]

See also #sub! #strip! #strip #succ also in 4.1 · 4.0 · 3.4 · 3.3 · 3.2 · 3.0

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