Ruby 1.9.2 リファレンスマニュアル > ライブラリ一覧 > 組み込みライブラリ > Arrayクラス > rotate!

instance method Array#rotate!

rotate!(cnt=1) -> self

Rotates _self_ in place so that the element at +cnt+ comes first, and returns _self_. If +cnt+ is negative then it rotates in counter direction.

a = [ "a", "b", "c", "d" ]
a.rotate!        #=> ["b", "c", "d", "a"]
a                #=> ["b", "c", "d", "a"]
a.rotate!(2)     #=> ["d", "a", "b", "c"]
a.rotate!(-3)    #=> ["a", "b", "c", "d"]

[SEE_ALSO] Array#rotate