substr outside of string

kulls has asked for the wisdom of the Perl Monks concerning the following question:

Hi,
Can anyone suggest me how to get ride of this error/ capture this error when my search index is more than the length of the string ?.

#!c:\bin\perl
use warnings;
my $str="name";
my $index=12;
my $s=substr($str,$index,1);
print $s;

__OUTPUT__

substr outside of string at - line 3.
Use of uninitialized value in print at - line 4.
[download]

Can I add this line before the assignment ? Is there any other option ?

exit if(length($str)< $index);
[download]

Thanks
-kulls

Comment on substr outside of string Select or Download Code

Replies are listed 'Best First'.
Re: substr outside of string by syphilis (Archbishop) on Sep 09, 2006 at 10:21 UTC
There's actually no error - all you're seeing is a couple of warnings because you have warnings enabled. If you really want to exit if the substr is outside of the string, then I can't think of any option significantly different to the one you've suggested. If you're more interested in just not seeing the warnings you could disable warnings altogether or change the code to: `use warnings; no warnings ('uninitialized', 'substr'); my $str="name"; my $index=12; my $s=substr($str,$index,1); print $s;` [download] Cheers, Rob	[reply] [d/l]
Re^2: substr outside of string by hgolden (Pilgrim) on Sep 09, 2006 at 13:49 UTC
Rob is right that it's just throwing a warning and not an error. The question is what you want to happen if the index is greater than the length of the string. If exiting is what you'd like, then you have a fine solution. If you're happy to print a blank, then you don't have to worry too much about the warning at all. If you'd like a different behavior if the index is greater than the string length, then set up a conditional: `if (length($str) < $index) { $s=substr($str,$index,1); } else { whatever else }` [download] I hope this helps, and reply if you need any more help. Hays Edit: Removed the poorly placed `my`	[reply] [d/l] [select]
Re^3: substr outside of string by ikegami (Patriarch) on Sep 09, 2006 at 18:40 UTC
Your `my` is rather useless inside the "then" clause. May I recommend the following variation: `my $s = (length($str) < $index ? substr($str, $index, 1) : '' # or undef, or die, or ... );` [download]	[reply] [d/l] [select]
Re^4: substr outside of string by hgolden (Pilgrim) on Sep 09, 2006 at 19:29 UTC
Re^3: substr outside of string by Anonymous Monk on May 03, 2012 at 05:23 UTC
Pardon me if I am wrong, but shouldn't it be `if (length($str) > $index) { $s = substr($str, $index, 1); } else { whatever else }` [download]	[reply] [d/l]