Shifts the first value of the array off and returns it, shortening the
array by 1 and moving everything down. If there are no elements in the
array, returns the undefined value. If ARRAY is omitted, shifts the
array within the lexical scope of subroutines and formats, and the
array outside a subroutine and also within the lexical scopes
established by the
Starting with Perl 5.14,
shift can take a scalar EXPR, which must hold a
reference to an unblessed array. The argument will be dereferenced
automatically. This aspect of
shift is considered highly experimental.
The exact behaviour may change in a future version of Perl.