shift applies to an array, as in, shift @a or, shift(@a). It removes the first (i.e., 0th) element from the array, shifting the remaining elements back by one (hence the name, I suppose), and returns the first element as its value.

So, if you have an array, initialized like this: 

my @a = ( 'a', 'b', 'c');

my $x = shift @a;

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then after this code executes, $x will contain the scalar value, 'a', and @a will contain, ( 'b', 'c' ).

In lexical scope (i.e., within a subroutine), shift by itself, without any arguments, implicitly acts upon the variable @_, which contains the subroutine's arguments.

At file scope (i.e., outside of any subroutine), it implicitly operates instead upon @ARGV (also known as ::@ARGV, or main::@ARGV), which contains the command line parameters passed to the script.

See the docs, "shift".

dmm

There are no stupid questions -- just stupid-making responses

In reply to Re: what does shift do? by dmmiller2k
in thread what does shift do? by dev2000

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