The following is another way when Autovivification is not desired.

if (exists $hash_ref->{$block} && !defined $hash_ref->{$block}->{$libN
+ame}) {
   print "This is a test\n";
}

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In reply to Re: Strange Hash related bug, keys are created by themselves! by marioroy
in thread Strange Hash related bug, keys are created by themselves! by mak007

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