How can I avoid warnings in Perl?

Question

I have a small piece of code for printing the contents in a text file like this,

use strict;
use warnings;

open (FILE, "2.txt") || die "$!\n";

my $var = <FILE>;
while ($var ne "")
{
    print "$var";
    $var = <FILE>;
} 

Text file is,

line 1
line 2
line 3 

After running the code i am getting a warning like this,

line 1
line 2
line 3
Use of uninitialized value $var in string ne at del.pl line 10, <FILE> line 3.

How to overcome this warning.

Answer 1

The quickest fix is probably to replace

while ($var ne "")

with

while (defined $var)

Answer 2

The common idiom for reading from a file is this:

open my $fh, '<', $file or die $!;

while (defined(my $line = <$fh>)) {
    print $line, "\n";
}

Although the while loop implicitly tests for whether the result of the assignment is defined, it's better to do the test explicitly for clarity.

Answer 3

I always use:

while(<FILE>) {
 print $_;
}

No such problems...