use of uninitialized value in substitution iterator

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

I'm following one of the answers to Forced resolution of environment variables in order to create a small sub to manage incoming data containing environment variables, but I seem to get the error "use of uninitialized value in substitution iterator". From http://www.sitepoint.com/forums/printthread.php?threadid=114018, I can understand the problems around changing $_ inside a sub, and have adjusted my code accordingly (I think!), but I can't see what else I need to change to get the substitution to work. Anyway, here's the code...

sub sub_env {
        my($in_string)=@_;
        $in_string =~ s/\$([A-Z0-9_]+)/$ENV{$1}/g;
        return $in_string;
}
[download]

Thanks for your help.

Comment on use of uninitialized value in substitution iterator Download Code

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Re: use of uninitialized value in substitution iterator by borisz (Canon) on Nov 11, 2004 at 11:40 UTC
try: `s/\$([A-Z0-9_]+)/$ENV{$1}\|\|''/eg;` [download] or whatever you like to do if the environment var is not there. Boris	[reply] [d/l]
Re^2: use of uninitialized value in substitution iterator by furrypop (Novice) on Nov 11, 2004 at 15:10 UTC
OK, so it was a "null return" from the environment hash, not something to do with $_? I guess that makes more sense. Thanks.	[reply]