You need to set $subject to some value first (strict will not allow the code to run otherwise.) Try this: 
use CGI;
use strict;

my $query = CGI->new();
my $subject = $query->param( 'subject' );

unless( defined $subject && $subject ) { 
   ...

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The calling convention of my $query = CGI->new(); is generally prefered, your way (my $query = new CGI;)is deprecated.

You should test that subject is both defined and that it has some value, as $subject = '' is defined but probably not what you want. You might want a regex like $subject =~ m/\w+/;to test that there are some characters in subject at the very least.

My question is $query an object instance of new CGI constructor? $query is now an instance of the CGI object and so it allows you access to the CGI modules methods.

--tidiness is the memory loss of environmental mnemonics

In reply to Re: Redirect and using CGI constructor by EvdB
in thread Redirect and using CGI constructor by Anonymous Monk

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