shuffle!(*args)
public
Shuffles elements in self in place.
a = [ 1, 2, 3 ]
a.shuffle!
a
The optional rng argument will be used as the random number
generator.
a.shuffle!(random: Random.new(1))
Show source
static VALUE
rb_ary_shuffle_bang(int argc, VALUE *argv, VALUE ary)
{
VALUE opts, randgen = rb_cRandom;
long i, len;
if (OPTHASH_GIVEN_P(opts)) {
VALUE rnd;
ID keyword_ids[1];
keyword_ids[0] = id_random;
rb_get_kwargs(opts, keyword_ids, 0, 1, &rnd);
if (rnd != Qundef) {
randgen = rnd;
}
}
rb_check_arity(argc, 0, 0);
rb_ary_modify(ary);
i = len = RARRAY_LEN(ary);
RARRAY_PTR_USE(ary, ptr, {
while (i) {
long j = RAND_UPTO(i);
VALUE tmp;
if (len != RARRAY_LEN(ary) || ptr != RARRAY_CONST_PTR(ary)) {
rb_raise(rb_eRuntimeError, "modified during shuffle");
}
tmp = ptr[--i];
ptr[i] = ptr[j];
ptr[j] = tmp;
}
}); /* WB: no new reference */
return ary;
}