Actually not. If you look at the original question, all values for the keys of %set2 should be set to undef. undef @set2{keys %set1}; leaves the original value in the hash. @set2{keys %set1}=undef; performs exactly as the original foreach $key (keys %set1) { $set2{$key} = undef; }.

In fact @set2{keys %set1}= (undef) x scalar keys %set1; is more correct (thanks to Zaxo for providing it), but might be slower.

In reply to Re: Re: Re: Fast Way to Combine Two Hashes by mirod
in thread Fast Way to Combine Two Hashes by arunhorne

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