Array#rotate!

array.rotate! → self

array.rotate!(count) → self

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;
}

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

When no argument given, rotates the first element to the last position:

Example

a = [:foo, 'bar', 2, 'bar']
a.rotate! # => ["bar", 2, "bar", :foo]

When given a non-negative Integer count, rotates count elements from the beginning to the end:

Example

a = [:foo, 'bar', 2]
a.rotate!(2)
a # => [2, :foo, "bar"]

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

Example

a = [:foo, 'bar', 2]
a.rotate!(20)
a # => [2, :foo, "bar"]

If count is zero, returns self unmodified:

Example

a = [:foo, 'bar', 2]
a.rotate!(0)
a # => [:foo, "bar", 2]

When given a negative Integer count, rotates in the opposite direction, from end to beginning:

Example

a = [:foo, 'bar', 2]
a.rotate!(-2)
a # => ["bar", 2, :foo]

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

Example

a = [:foo, 'bar', 2]
a.rotate!(-5)
a # => ["bar", 2, :foo]

See also #rotate #sample #rindex #select also in 4.1 · 4.0 · 3.4 · 3.2 · 3.1 · 3.0

‹ prev#rotate next ›#sample