readline() on closed file-handle is coming when reading the file

ulaksh has asked for the wisdom of the Perl Monks concerning the following question:

readline() on closed filehandle is coming when executing the perl script. I am trying to get the number of line in file which contain the X. I am not getting where is the issue.

#!/usr/bin/perl
use strict;
use warnings;


my ($filename, $lines_num, $line, $c);

$lines_num = 0;
$filename = "input.txt";
open my $in,  "<", $filename;
while ($line = <$in>)
{
    $c = substr($line, 0, 1);
    if (lc($c) eq "x")
    {
        $lines_num++;
    }
}
close($in);

print "In " , $filename, " there are ",
    $lines_num, " lines that start with \"X\".\n";
[download]

my input file contains as below
X
XX
XXX
XXXX
XXXXX
XXXXXX
XXXXXXX
XXXXXXXX
XXXXXXXXX
XXXXXXXXXX
XXXXXXXXXXX
XXXXXXXXXXXX
XXXXXXXXXXXXX
XXXXXXXXXXXXXX
XXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX
[download]

And my output show "readline() on closed filehandle $in at filehandleoperator.pl line 12."

Comment on readline() on closed file-handle is coming when reading the file Select or Download Code

Replies are listed 'Best First'.
Re: readline() on closed file-handle is coming when reading the file by philiprbrenan (Monk) on Aug 30, 2012 at 22:38 UTC
Please add: `or die "Cannot open file";` [download] after the open.	[reply] [d/l]
Re^2: readline() on closed file-handle is coming when reading the file by johngg (Canon) on Aug 31, 2012 at 08:50 UTC
Or, even better: `or die "Cannot open file: $!";` [download] so that you can see the o/s error generated when the filehandle failed to open. Cheers, JohnGG	[reply] [d/l]
Re: readline() on closed file-handle is coming when reading the file by 2teez (Vicar) on Aug 30, 2012 at 23:41 UTC
OR, add `use autodie qw(open close);` just after `use warnings;` in your script. Your script should work fine, except you have other things in mind. For detailed information check autodie Cheers	[reply] [d/l] [select]