#!/usr/bin/perl
use warnings;

@this_array = ("b", "a", "d", "c");
foreach($this_array){
	print("$_\n");
}

##</code><code>##

Use of uninitialized value $_ in concatenation (.) or string at derp.pl line 7.

##</code><code>##

#!/usr/bin/perl
use warnings;

@this_array = ("b", "a", "d", "c");
foreach(@this_array){   # note @this_array not $this_array
	print("$_\n");
}