why perl does not throw exception ?

[WebGoat]

#!/usr/local/bin/perl
#@food  = ("apples", "pears", "eels");
#$l=push(@food, "eggs", "lard");
#($a, $b) = @food;
#$f = "@food";
#print $b;
($a, $b) = ($c, $d);
print $a;

it prints nothing . $c,$d has no value. then why they did not throws exception while attempting print null values

 

[TrojanWarBlade]

Because you did not ask it to!
Try adding -w to the end of your shebang line like this:

#!/usr/local/bin/perl -w

Now you should see your warnings.
Perl is quite happy to process scalars with no value so you have to specifically ask it to tell you about this issue.
Larry suggests that perl's biggest failure is that -w is not mandatory. I suggest you take that advice and use it for all your scritps.
Also it is generally considered wise to use strict; in all your scripts and declare all your scalars before use with my.


Trojan.

 

[WebGoat]

>Because you did not ask it to!
>Try adding -w to the end of your shebang line like this:

thank you , i'll use it from my next script. thanks for the tips.

>Also it is generally considered wise to use strict; in all >your scripts and declare all your scalars before use with my

i dont know even what is "use srtict" and "my"

i am at the chapter arrays and variables.but i saw some scripts which usues keuword "my". i dont understand that.

 

[TrojanWarBlade]

Have a read and come back later if the books don't explain things well enough.


Trojan.

 

[ishnid]

If you don't use warnings or strict, variable will be automatically assigned an undefined value when you first use them, regardless of whether they've been previously declared or not.

The main benefit of `strict' is that it prevents typos causing huge debugging headaches. For example:

$variable = 'blah';

print substr( $variab1e, 0, 2 );

Perl will happily try to get a substring of the undefined variable $variab1e (note that's it's a number one, not the letter `l' in the latter). Try debugging *that*.