while (my $ptfkey = <F2>)

##</code><code>##

while (<F2>) {
    $ptfkey = $_; # you can skip this using above suggestion
    $ptfpn = $ptfkey; # don't need this if just matching

    $ptfpn =~ m/^(\w+)/; # if only letters and numbers
    $ptfpn =~ m/^([\d\-\.]+)/; # if it's a float
    $F1hash{$1} = 1;
    }

##</code><code>##

if ($PartNumber =~ $Flhash{$PartNumber}) {

##</code><code>##

if (exists $F1hash{$PartNumber}) {

##</code><code>##

#!c:\perl\bin\perl -w
# note the addition of the -w

use diagnostics;
use strict;