Adding thousands separators to a number

Today Marco shared on his blog an idea how to add thousands separators on CLI with help of standard printf function, and Perl, and sed, and awk. So I want to extend his post with same thing but in PHP, Ruby and Python. Of course you can achieve same with printf functions of these langauages and setting correct locale, but it’s not as interesting as one-line things. So here we go…


There are many ways to achieve this. But I’m going to show the most short and clean variants :)) Let’s start with regular expressions usage. First way is to split string with regular expression into an array of chunks and then join them with comma clue, like this:

$ php -r 'echo implode(",", preg_split("/(?<=\d)(?=(\d{3})+$)/", $argv[1])) . "\n";' 1234

Also, you can use preg_replace() function:

$ php -r 'echo preg_replace("/(\d{1,3})(?=(\d{3})+$)/", "\\1,", $argv[1]) . "\n";' 1234

And finally you can simply use number_format() function:

$ php -r 'echo number_format($argv[1], 0, ".", ",") . "\n";' 1234


$ ruby -e 'puts ARGV[0].gsub(/(\d{1,3})(?=(\d{3})+$)/, "\\1,")' 1234


In fact I don’t have lot’s of practice in Python every-day usage, so if you know better variant, feel free to share it and point me that I’m shit ;))

$ python -c 'import sys,re; print re.sub(r"(\d{1,3})(?=(\d{3})+$)", "\\1,", sys.argv[1])' 1234


Basically this is alternative version of Marco’s variant, that I’ve just posted as a comment to his post :)) So I’m placing it here just to keep it for myself. In Perl you can achieve this with only assertions (like with preg_split() of PHP):

$ perl -pe 's/(?<=\d)(?=(\d{3})+$)/,/g' <<< 1234

Or with only one asserion:

$ perl -pe 's/(\d{1,3})(?=(\d{3})+$)/\1,/g' <<< 1234
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