Ah, I see.

Well, you need to make things equal before comparing them ... you are putting numbers 1..n as keys into %isthere, but try to get out $isthere{"00001"}. That will not work - the keys in %isthere are "1" etc.

This is what you need to make it work:

  $isthere{$_} = "yes" for map {$_+0} @list;
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Christian Lemburg
Brainbench MVP for Perl
http://www.brainbench.com