A one-liner for visually verifying the output: 

# assumes the output is in $s;
print sort map{ substr $s, $_, 2 } 0..99;

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Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller
If I understand your problem, I can solve it! Of course, the same can be said for you.

In reply to Re: Friday Golf: All 2-digit combinations by BrowserUk
in thread Friday Golf: All 2-digit combinations by PhilHibbs

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