format number with comma separators?

[Chris Morris]

I'm brain dead and just trying to get formatted numbers in a task that's
already 10 tangents deep -- argh. Anyway, how can I sprintf (or
otherwise) this:

456778904

to this:

456,778,904

 

[Mark J. Reed]

I'm brain dead and just trying to get formatted numbers in a task that's
already 10 tangents deep -- argh. Anyway, how can I sprintf (or
otherwise) this:

456778904

to this:

456,778,904

Unless there's something I don't know about - a distinct possibility
- there's no built-in function to do this. You can, however,
do it with a regex. Assuming the numbers are all integers (no
decimal points), then this will work:

formatted_n = n.to_s.reverse.gsub(/...(?=.)/,'\&,').reverse

-Mark

 

[Robert Klemme]

Unless there's something I don't know about - a distinct possibility
- there's no built-in function to do this. You can, however,
do it with a regex. Assuming the numbers are all integers (no
decimal points), then this will work:

formatted_n = n.to_s.reverse.gsub(/...(?=.)/,'\&,').reverse

This fails for negative numbers in the range -100..-999 and all other
negative numbers with an amount of digits that is divisable by 3.

Alternative:

def format(num)
s = num.to_s

if s.include? ?.
pre, post = s.split '.'
"#{pre.reverse.gsub( /\d{3}(?=\d)/, '\&,' ).reverse}.#{post}"
else
s.reverse.gsub( /\d{3}(?=\d)/, '\&,' ).reverse
end
end

robert

 

[Robert Klemme]

Found this: http://www.rubygarden.org/ruby?FixNumFormat

Due to probs with negative numbers I added another version to that.

robert