Question

I’m looking to format a Long Float as currency in C. I would like to place a dollar sign at the beginning, commas iterating every third digit before decimal, and a dot immediately before decimal. So far, I have been printing numbers like so:

printf("You are owed $%.2Lf!\n", money);

which returns something like

You are owed $123456789.00!

Numbers should look like this

$123,456,789.00
$1,234.56
$123.45

Any answers need not be in actual code. You don’t have to spoon feed. If there are C-related specifics which would be of help, please mention. Else pseudo-code is fine.

Answer 1

Your printf might already be able to do that by itself with the ' flag. You probably need to set your locale, though. Here’s an example from my machine:

#include <stdio.h>
#include <locale.h>

int main(void)
{
    setlocale(LC_NUMERIC, "");
    printf("$%'.2Lf\n", 123456789.00L);
    printf("$%'.2Lf\n", 1234.56L);
    printf("$%'.2Lf\n", 123.45L);
    return 0;
}

And running it:

> make example
clang -Wall -Wextra -Werror    example.c   -o example
> ./example 
$123,456,789.00
$1,234.56
$123.45

This program works the way you want it to both on my Mac (10.6.8) and on a Linux machine (Ubuntu 10.10) I just tried.