Re: How do I print a large integer with thousands separators?

[Anonymous Monk]

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:	3	2489	8x10^8	8x10^13
while loop:	869k/s	60k/s	33k/s	18k/s
reverse:	465k/s	65k/s	47k/s	34k/s
lookahead:	571k/s	54k/s	34k/s	22k/s
manual:	270k/s	139k/s	95k/s	61k/s
le3manual:	1000k/s	135k/s	91k/s	59k/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)

[scottj]

Your test script was very educational for me. I'd never seen use of the Benchmark module before. It looks like you've certainly gotten a fast method for adding in the thousands separators.

For those who need something a bit easier to follow, I'd like to add the following to this topic:

#!/usr/bin/perl
use Number::Format;
my $num = 12349329824342;
my $nf = new Number::Format(-thousands_sep => ',');  
my $separated_num = $nf->format_number($num);