I haven't examined the code past the fact that your implementation and array_pad don't match up

#Returns a copy of the input padded to size specified by pad_size with
+ value pad_value.
#If pad_size is positive then the array is padded on the right, if it'
+s negative then on the left.
#If the absolute value of pad_size is less than or equal to the length
+ of the input then no padding takes place.
#int pad_size, mixed pad_value, array  input

sub array_pad{
    my($pad_size, $pad_value, @array) = @_;
    #this is just to get the absolute value of the pad_size
    my $temp = $pad_size;
    if($pad_size < 0){
        $temp = $temp * -1;
    }#if
    #first let's see if the pad_size is less than or equal to the arra
+y size, return 0 no padding
    my $input_size = @array;
    if($temp <= $input_size){
        return 0;
    }#if
    #since it didn't return 0, time to pad
    #if the pad_size is < 0, pad on the left, else the right
    if($pad_size < 0){
        my @retval;
        $temp = $temp - $input_size;
        for(my $i=0;$i<$temp;$i++){
            unshift(@array, $pad_value);
        }#for
        return @array;
    }#if
    else{
        $temp = $pad_size - $input_size;
        for(my $i=0;$i<$temp;$i++){
            push(@array, $pad_value);
        }#for
        return @array;
    }#else
}#array_pad

sub p{my($i,$z,@f)=@_;abs$i>@f&&$i<0?@f=(($z) x abs($i+@f),@f):(@f[@f.
+.$i-1]=($z)x($i-@f));@f}

use Test::More tests => 4;

my @x = 1 .. 5;

is_deeply([p( 3, 'x', @x)], [array_pad( 3, 'x', @x)]);
is_deeply([p(-3, 'x', @x)], [array_pad(-3, 'x', @x)]);
is_deeply([p( 7, 'x', @x)], [array_pad( 7, 'x', @x)]);
is_deeply([p(-7, 'x', @x)], [array_pad(-7, 'x', @x)]);

__END__
1..4
not ok 1
#     Failed test (golfing.array_pad.pl at line 43)
#     Structures begin differing at:
#          $got->[0] = '1'
#     $expected->[0] = '0'
not ok 2
#     Failed test (golfing.array_pad.pl at line 44)
#     Structures begin differing at:
#          $got->[0] = '1'
#     $expected->[0] = '0'
ok 3
ok 4
# Looks like you failed 2 tests of 4.
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