Where did you get this sprintf "%0${len}d", $number;
The sprintf documentation, perhaps? 
printf '<%06s>', 12;   # prints "<000012>"

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BTW: The thread you responded to is 7 years old.
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No matter how great and destructive your problems may seem now, remember, you've probably only seen the tip of them. [1]

In reply to Re^3: front-pad a number with zero's by andreas1234567
in thread front-pad a number with zero's by deprecated

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