Format a thousand separator in C with FreeBSD

Question

How to format a thousand separator in C with FreeBSD? I obtain the code from one of the answers here How can I format currency with commas in C? and it is working in my Ubuntu Linux system but not in my FreeBSD 11.4 and 14-CURRENT systems.

#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;
}

Answer 1

The printf manpage(3) says:

`'' (apostrophe) Decimal conversions (d, u, or i) or the integral portion of a floating point conversion (f or F) should be grouped and separated by thousands using the non-monetary separator returned by localeconv(3).

so, it uses the locale separator.

You can do something like that:

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

int main(void)
{
    const char sep = '\'';

    setlocale(LC_NUMERIC, ""); 
    localeconv()->thousands_sep[0] = sep;

    printf("$%'04.2Lf\n", 123456789.00L);
    printf("$%'04.2Lf\n", 1234.56L);
    printf("$%'04.2Lf\n", 123.45L);

    return 0;
}

then compile like this:

cc -o myprog myprog.c

which will output:

./myprog
$123'456'789.00
$1'234.56
$123.45