use List::Util 'shuffle';

my @fileData = shuffle map { "$_\n" } 1 .. 20, (1) x 5;

my $linenumber=1;
foreach my $line(@fileData) {
   $linenumber=$linenumber+1;
   if ($line =~ m/^1$/) {
       print "$linenumber\n";
   }
}
[download]

Output:

6
7
8
16
17
25
[download]

Are you sure you're reading your data correctly?

My data must be something other than what I think it is. I'll revisit it. Thanks.

You might try m/^1\s*$/ for your regular expression.
-- gam3
A picture is worth a thousand words, but takes 200K.

How are you populating your @fileData array? Is there any reason not to iterate over the filehandle directly?

use strict;
use warnings;

my $infile = 'whatever';
open my $fh, '<', $infile or die "Couldn't open '$infile' for read: $!
+\n";

while ( my $line = <$fh> ) {
   print "$.\n" if $line =~ m/^1$/;
}
[download]

When I run your code with my own input, the output I get is the line number plus 1 of the lines which just contain 1\n. To get the actual line number:

$linenumber=1;
foreach $line(@fileData) {
   if ($line =~ m/^1$/) {
       print "$linenumber\n";
   }
   $linenumber++;
}
[download]

tinita is more precise. $. is used with filehandles.

You could also use the special variable $. instead of $linenumber.

not while looping over an array, only when reading lines from a filehandle.

Some say premature optimization is the root of all programming evils (but then they must not have ever used COBOL). Overly concise code is generally a bad idea in production, too. However, I think that without hurting clarity it's always better to remove code to fix a problem rather than moving it around. This can often be done simply for off-by-one errors.

foreach $line ( @fileData ) {
    $linenumber++;
    if ( $line =~ m/^1$/) {
        print "$linenumber\n";
    }
}
[download]

Then there's the issue of idiomatic usage, which may or may not lead one to use $_, implicit matching against $_, or 'for' instead of 'foreach', depending one their views. This leads to code about as legible as the previous for many Perl coders, but I think it's fair to call it a matter of preference.

for ( @fileData ) {
    $linenumber++;
    if ( m/^1$/ ) {
        print "$linenumber\n";
    }
}
[download]

Which shouldn't be confused at all with golf, which does hinder legibility somewhat.

$l++,/^1$/&&print$l.$/for@f;
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Have you used the debugger on this script, and really looked at what each each $line looks like?

throop

Given that the OP is searching for strings that end with a newline, I doubt chomping is going to help!