Just extend your existing regular expression a bit will do the trick -
use strict;

while (<DATA>) {
    s/(\d+|\.)/ $1 eq '.' ? '' : sprintf "%03d", $1 /eg;
    print;
}

__DATA__
127.0.0.1
256.123.12.1
256.12.31.21

[download]
And the output -
127000000001
256123012001
256012031021

[download]

In reply to Re: create filename from IP# by Roger
in thread create filename from IP# by belize

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