Honestly,

push @num, splice(@array, int rand @array, 1);
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This totally made my day - the efficiency. In an extension of the original requirement, I needed to generate long fixed length strings from random elements in an array.. this is so much faster than what I was using.. I've no absolute requirement for total uniqueness, but it looks like no letter is being repeated in multiple runs of:

#!/usr/bin/perl -w

use strict;

my $counter = "0";
my $randstring;
my @testarray = ( 'a' .. 'z', 'A' .. 'Z', '0' .. '9' );

do { $randstring .= splice(@testarray, int rand @testarray,1); 
     ++$counter;
} until $counter == 62; 

print "\n\$randstring:  $randstring\n\n";
[download]

-hsinclai