dir.txt = [ dir1.txt, dir2.txt, dir3.txt]

use Win32::DirSize;
open (FILE, "dir.txt") || die "can not open file\n";
chomp (@file = <FILE>);
close FILE;
#$f = "dir1"; # If I unpound this and pound out the foreach #loop works.
foreach $f (@file) {
 	my $Result = dir_size(
	$f,
   	my $DirInfo, 
 	);