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    <p>Always 'use strict;' and instead of <code>!# /usr/bin/perl -w</code>. Use <code>use warnings;</code>. It's a lot more flexible. I rewrote your program:</p> <p>Here's a few other hints:</p> <ul> <li>Don't use <code>$_</code> when you don't have to. There are problems with <code>$_</code> because of its <em>global</em> nature. It has to be used with <code>map</code> and <code>grep</code>, and people use it with <code>shift</code>, but most of the time, you end up having go assign it to something else anyway, so it doesn't do what it was suppose to do: Make your program <em>more readable</em>. In your case, you get an input, then assign it to <code>$_</code>. No need to do that. </li> </ul> <p>This works just as well:</p> <pre><code>$query_string =~ s/\W//gi; $query_string =~ s/\U$_/\L$_/gi; </code></pre> <ul> <li>You're getting <em>arrays</em> and <em>scalars</em> mixed up.</li> </ul> <p>This:</p> <pre><code>my @forward = reverse ($backwards[0]); </code></pre> <p>is assuaging your string <code>$backwards[0]</code> <code>$forward[0]</code>. There is no <code>$forward[1]</code>. The entire string is being assigned to the first element of the array.</p> <p>Maybe you want to do this:</p> <pre><code>my @forward = split //, reverse ($backwards[0]); </code></pre> <p>This splits the string <code>reverse ($backwards[0]</code> per letter, and puts each letter into <code>@forward</code>.</p> <p>I'm not sure what the input is. Why are you splitting on <code>=</code>? Does the user enter a palindrome?</p> <pre><code>whatisit=tisitahw </code></pre> <p>Or like this:</p> <pre><code>madam, I am Adam. </code></pre> <p>If it is the latter, why go through all of the conniptions?</p> <pre><code>#! /usr/bin/env perl use strict; use warnings; use feature qw(say); print "Enter String: "; chomp ( my $query_string= &lt;STDIN&gt; ); $query_string =~ s/[\W_]//g; if ( lc $query_string eq lc reverse $query_string ) { say "Hey, that's a palindrome"; } say "No, it's not a palindrome"; } </code></pre> <p>I use <code>s/[\W_]//g</code> to remove all spaces, and other non-letter stuff. It does keep numbers. The <code>[\W_]</code> is needed because <code>\W</code> doesn't include underscores. The <code>g</code> on the end means do this as many times as necessary in the string and not just the first occurrence.</p> <p>Then, all I have to do is compare the uppercase string to its reversed self. No need to step through an array. The <code>reverse</code> function handles everything for you. The only issue is that this is destructive because I munge the input string, so it doesn't match the user's input at the end of the program.</p> <pre><code>$ program.pl String: Madam I am Adam. No, it's not a palindrome $ $ program.pl String: Madam I'm Adam. Hey, that's a palindrome </code></pre> <p>What you should do is make this a function:</p> <pre><code>#! /usr/bin/env perl use strict; use warnings; use feature qw(say); print "Enter the string: "; ( my $string = chomp &lt;STDIN&gt; ); if ( palindrome( $string ) ) { say "Hey, $string is a palindrome"; } say "Sorry, $string is not a palindrome"; } sub palindrome { my $palindrome = shift; $palindrome =~ s/[\W_]//g; if ( lc $palindrome ne lc reverse $palindrome ) { return; # Not a palindrome } return $palindrome; } </code></pre>
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