My program hangs

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

I am trying to write a program to print all matching lines of a pattern

#!/usr/bin/perl;
use warnings;
use strict;
my $filename = 'C:\Perl\example.txt';
open (my $fh, '<' ,$filename) or die "ERROR: could not open $filename:
+ $!";
while (<>) {
if (/fred/) {
print ;
}
}
close ($fh);
[download]

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Re: My program hangs by Corion (Patriarch) on Jun 23, 2014 at 08:16 UTC
You are reading from the wrong filehandle: `open (my $fh, '<' ,$filename) or die "ERROR: could not open $filename: + $!"; while (<>) {` [download] Instead of reading from standard input (or the file passed on the command line), you want to read from the filehandle you just opened, `$fh`: `while (<$fh>) {` [download]	[reply] [d/l] [select]
Re: My program hangs by vinoth.ree (Monsignor) on Jun 23, 2014 at 10:10 UTC
Hi, Your program is not hangs,Its waiting for input from you, when you write <> it is a abbrivation for <STDIN>, so it will read either from a file specified on the command line or from stdin if no file is given. As told by Corion, you need to use `<$fh>`, to read from your file handle. *All is well*	[reply] [d/l]
Re: My program hangs by 1s44c (Scribe) on Jun 23, 2014 at 13:13 UTC
Like Corion says you are reading from the wrong filehandle. But: `#!/usr/bin/perl;` [download] You're on unix. `my $filename = 'C:\Perl\example.txt';` [download] You're on windows. I'm confused, they can't be both right?	[reply] [d/l] [select]
Re^2: My program hangs by Corion (Patriarch) on Jun 23, 2014 at 13:18 UTC
Windows does not care for the hashbang line of a script. Perl does care for the line, respectively, for the switches on that line. In that sense, they can both be right.	[reply]