Pops and returns the last value of the array, shortening the array by one element.
Returns the undefined value if the array is empty, although this may also
happen at other times. If ARRAY is omitted, pops the @ARGV
array in the
main program, but the @_
array in subroutines, just like shift.
Starting with Perl 5.14, pop can take a scalar EXPR, which must hold a
reference to an unblessed array. The argument will be dereferenced
automatically. This aspect of pop is considered highly experimental.
The exact behaviour may change in a future version of Perl.