When you pass an array as an argument to sub-routine it gets flattened. That is, as far as the sub-routine knows, its no longer an array, rather its now a list of its scalar elements. So shift will only get the first scalar in the array @_, not the entire list.

To illustrate:

@foo = (1,2,3);
process_array(@foo);

sub process_array {
    # the special @_ variable now holds (1,2,3), NOT (@foo)
    $var1 = shift;    # $var1 will only get '1'.
    $var2 = shift;    # $var2 will only get '2'.
    $var3 = shift;    # $var3 will only get '3'.

}
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To assign the entire argument list you would have to code the sub-routine like this:

sub process_array {
    @args = @_;

}
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or using an array reference:

sub process_array {
    $args = \@_;

}
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Hope that helps.

Amel - f.k.a. - kel