I benchmarked the following methods

'while loop' is the "1 while..." method.
'reverse' is the Andrew Johnson method.
'lookahead' is the stefp method.
'manual' is the one using substr.
'le3manual' is the one using substr with an initial check to make sure there are more than three digits.

Number:324898x10^88x10^13
while loop:869k/s60k/s33k/s18k/s
reverse:465k/s65k/s47k/s34k/s
lookahead:571k/s54k/s34k/s22k/s
manual:270k/s139k/s95k/s61k/s
le3manual:1000k/s135k/s91k/s59k/s

Nk/s = N thousands of completed commafications per second

Basically it looks like the substr method, with the <=3 clause, obliterates the competition. I feel dirty saying it, but looks like a one-liner regexp is not the best solution.

(My test script is available here)

In reply to Re: How do I print a large integer with thousands separators? by Anonymous Monk
in thread How do I print a large integer with thousands separators? by miblo

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