I have this code which reads a data file and compares values between lines of that data
it reads from the top of the file to the bottom. How do I change this to read from the bottom of the file (last entry) to the top (first entry) ? 
while (@lines > 12) {
    
    # check first 7 lines against the 8th line
    my @vals = split /\s+/, $lines[12];
    my @chk = split /\s+/, join(' ', @lines[0..11]);
    my %match;
    foreach my $val (@vals) {
        $match{$val}++ if grep { $val eq $_ } @chk;
    }
    my @match = sort keys %match;
    my @nomatch = grep { not exists $match{$_} } @vals;

    my $match = @match;
    my $nomatch = @nomatch;
    #my $vals = @vals;
    #my $lines = @lines;
    #print NUMBER "$lines @lines \n\n";
    
    if ($match == 0) { 
        $zero ++ 
        } 
    if ($match == 1) { 
        $one ++ 
        }
    if ($match == 2) { 
        $two ++ 
        }
    if ($match == 3) { 
        $three ++ 
        }
    if ($match == 4) { 
        $four ++ 
        }
    if ($match == 5) { 
        $five ++ 
        }
    if ($match == 6) { 
        $six ++ 
        }
        
# do whatever you want with the matches and no-matches    
    print MATCH "$line: \tmatch = @match\n";
    print NOMATCH "$line: \tnomatch = @nomatch\n";
    
    
    
    $line++;

    # get rid of first line so next loop will be 2-6 and so on
    shift @lines;
}

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In reply to Reversing the action of the while loop by Scotmonk

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