I could be on the wrong track here, however are you defining variables before you use them? The line: 
  print "The string is $foo\n";

[download]
may give you an "uninitialised value, as $foo may not be defined yet. whereas: 
  my $foo;
  # some code
  print "The string is $foo\n";

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should be better - as $foo has been defined.. Referencing into hashes, only to discover that the particular key you're trying to use does not exists is another area that results in a very similar problem :)

-- Ian Stuart
A man depriving some poor village, somewhere, of a first-class idiot.

In reply to Re: The -w switch on a web application by kiz
in thread The -w switch on a web application by Heidegger

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