I can't seem to get this to work. I thought I'd try this out to compare it for speed with the hash version mentioned later. It never prints the pid in use message even though the pid exists in the array. How do I debug this statement

if ($_ == $xpid) {
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To see why the match is not being made ? I tried

print @$_ ;
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This gives me the value I expect to see (i.e. a pid) but even though $xpid appears to have the same value the if is not evaluating to true ?