I figured it out. Thank you for all of the help! 

use Tk;
use strict;
use warnings;

my $mw=new MainWindow;
my @header = ("FHT_neg45","FHT_0","FHT_45","FHT_90","OHT_neg45","OHT_0
+","OHT_45","OHT_90");
my $button = $mw->Button(-text=>"temp",
    -command=> \&button)->pack();
MainLoop;

sub button {
    #Read BJSFM_out.prn into an array @data
    my $filename="BJSFM_out.prn";
    open my $fh, '<', $filename or die "Can't find $filename!";
    my $string="1DO YOU WANT INSTRUCTIONS?";
    my @data= map {chomp; $_} <$fh>;
    my $n=0;
    foreach my $line (@data) {
        if ($line eq $string) {
            $line = $header[$n];
            $n++;
        }
    }
    open my $write_fh, '>', 'temp.txt' or die $!;
    print $write_fh join "\n",@data;
    close $write_fh;
}

[download]

In reply to Re^4: Replace Array Elements with Hash Values by shortyfw06
in thread Replace Array Elements with Hash Values by shortyfw06

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.