in reply to Re^2: How to print the lines immediately above and below a matching line?
in thread How to print the lines immediately above and below a matching line?

Then you need to change your code. Something like: 
my $data = <DATA>;
chomp $data;
if ($this_line =~ /\Q$data/)

[download]
  • Comment on Re^3: How to print the lines immediately above and below a matching line?
  • Download Code

Replies are listed 'Best First'.
Re^4: How to print the lines immediately above and below a matching line?
by Bio90 (Initiate) on Nov 25, 2012 at 13:55 UTC
    I have tried that but it has returned a "Use of uninitialised value $data". I do not understand - surely $data is initialised by my $data = <DATA>;?
[reply]
[d/l]
[select]

      Show that code? Where did you add the line?

[reply]
        Here is the code with the change
        use strict;
use warnings;

open( my $fh, '<', 'input.txt') or die "Error opening file - $!\n";
open OUT, ">", "output.txt" or die "could not open output.txt $! \n";

my $this_line = "";
my $do_next = 0;
my $data = <DATA>;

while(<$fh>) {
    my $last_line = $this_line;
    $this_line = $_;
    
    chomp $data;
    if ($this_line =~ /\Q$data/) {
        print OUT $last_line unless $do_next;
        print OUT $this_line;
        $do_next = 1;
    } else {
        print OUT $this_line if $do_next;
        $last_line = "";
        $do_next = 0;
    }
}
close ($fh);

__DATA__
4386_7#8
4350_7#6
4414_1#6

        [download]
[reply]
[d/l]

In Section Seekers of Perl Wisdom