Use lookahead:
$t = "1,2,3,4\n8,9,10,11\n7,8,9,10,\n12,13,14,15\n";;
print $t;;
1,2,3,4
8,9,10,11
7,8,9,10,
12,13,14,15
$t =~ s[(\D|^)(?=\d(?:\D|$))][${1}0]g;;
print $t;;
01,02,03,04
08,09,10,11
07,08,09,10,
12,13,14,15
With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.