use strict; 

my $string = 'hello world'; 
print substr($string,'O',5)."\n";

##</code><code>##

perl absurd.pl
hello

##</code><code>##

use strict; 
use warnings;

my $string = 'hello world'; 
print substr($string,'O',5)."\n";

##</code><code>##

perl absurd.pl
Argument "O" isn't numeric in substr at absurd.pl line 4.
hello