________________________________________
From: Rob Dixon [rob.di...@gmx.com]
Sent: 09 November 2012 17:17
To: beginners@perl.org
Cc: Nemana, Satya
Subject: Re: variable definition error not caught when using strict and warnings
On 09/11/2012 17:08, Nemana, Satya wrote:
> Hi
>
> I am a little confused with this program
>
> Program:
> use strict;
> use warnings;
>
> if ($999 == 1056)
> {
> print ("\nequal");
> }
> else
> {
> print ("\nnot equal");
> }
>
> What I expect: Perl to throw me an error as $999 variable is not defined, but
> perl executes the code with a warning.(I don't expect the code to compile at
> all)
>
> Output:
> Use of uninitialized value in numeric eq (==) at wrong1.pl line 4.
>
> not equal
>
>
> However, if I replace $999 with $num (which is not defined or initialized), I
> get the following error
>
> Global symbol "$num" requires explicit package name at wrong1.pl line 4.
> Execution of wrong1.pl aborted due to compilation errors.
>
> What is happening with the top program?
Hello Satya
The variable $999 holds the 999th capture from the most recent regular
successful expression match. Since you have no regular expressions in
the program it is left undefined. It would be very unusual to have so
many captures in a regex but Perl does support it.
Rob
Hi Rob
Thank you.
I will give a read of the perl regular expression manual.
Actually $999 resulted in a typo was i wanted to compare another variable with
999.
Not from a regular expression.
But it took a while for me to find the culprit as the intended code was never
hit.
I was trying to understand why I never got an error during the compile itself.
Thanks for answering.
Regards,
Satya
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