in reply to Re: Replace Array Elements with Hash Values
in thread Replace Array Elements with Hash Values

Two further improvements:

First, toolic is right about the need for chomping, so 

my @data = map { chomp; $_ } <$fh>;

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and of course check the open: 
open my $write_fh, '<', 'temp.txt' or die $!;

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Re^3: Replace Array Elements with Hash Values
by Cristoforo (Curate) on Jun 13, 2012 at 18:19 UTC
    Just an observation. List::MoreUtils has a function apply which does the chomp and passes the modified, (line less the newline), line to @data

    my @data= apply {chomp} <$fh>;.

    Chris

    Update: Or more simply, chomp(my @data = <$fh>);

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      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;
}

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Re^3: Replace Array Elements with Hash Values
by shortyfw06 (Beadle) on Jun 13, 2012 at 18:13 UTC

    I tried to run the following and it replaces $string with %header rather than $string with $header[0], $header1, etc. Also, I thought my print command would add the newlines but it doesn't.

    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 $n=0;
    for (@data) {
        if ($_ eq $string) {
            $data[$n] = $header[$n];
            $n++;
        }
    }
    open my $write_fh, '>', 'temp.txt' or die $!;
    print $write_fh join " ",@data,"\n";
    close $write_fh;
}

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