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It has to do with how foreach (and for, which is an exact synonym) works. foreach will construct the entire list, then iterate through it. This can be very memory-intensive, which will slow the processing speed (due to cache misses and virtual memory issues.) A nearly exact rewrite of foreach in terms of while would look something like:
foreach my $n (<*.*>) { # do stuff } ---- my @list = <*.*>; my $i = 0; while ($i <= $#list) { my $n = $list[$i]; # do stuff } continue { $i++; }

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The idea is a little like C++ templates, except not quite so brain-meltingly complicated. -- TheDamian, Exegesis 6

Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.


In reply to Re: Re: Re: Efficient processing of large directory by dragonchild
in thread Efficient processing of large directory by Elliott

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