my %stuff = ( moo => "cow",
              test => "blue",
              dark => "black",
              white => "light",
              house => "home",
              "all things" => "multi",
              money => "value",
        );
  while (my ($k, $v) = each(%stuff)) {
     if { $input =~ /$k/ } {
        change = $v;
        last;   # break out of the loop now
   }