Method: Array#rotate!

Defined in:
array.c

#rotate!(count = 1) ⇒ self

Rotates self in place by moving elements from one end to the other; returns self.

With non-negative numeric count, rotates count elements from the beginning to the end:

[0, 1, 2, 3].rotate!(2)   # => [2, 3, 0, 1]
  [0, 1, 2, 3].rotate!(2.1) # => [2, 3, 0, 1]

If count is large, uses count % array.size as the count:

[0, 1, 2, 3].rotate!(21) # => [1, 2, 3, 0]

If count is zero, rotates no elements:

[0, 1, 2, 3].rotate!(0) # => [0, 1, 2, 3]

With a negative numeric count, rotates in the opposite direction, from end to beginning:

[0, 1, 2, 3].rotate!(-1) # => [3, 0, 1, 2]

If count is small (far from zero), uses count % array.size as the count:

[0, 1, 2, 3].rotate!(-21) # => [3, 0, 1, 2]

Related: see Methods for Assigning.

Returns:

  • (self) 


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# File 'array.c', line 3248

static VALUE
rb_ary_rotate_bang(int argc, VALUE *argv, VALUE ary)
{
    long n = (rb_check_arity(argc, 0, 1) ? NUM2LONG(argv[0]) : 1);
    rb_ary_rotate(ary, n);
    return ary;
}