Display an integer comma separated in C?

Question

How can we display an integer comma separated in C?

For example if int i=9876543, result should be 9,876,543.

The answers in "How to format a number from 1123456789 to 1,123,456,789 in C?" do not provide a portable answer or one that works for all `int` (INT_MIN fails for many). The accepted answer here is portable and works for INT_MIN. — chux - Reinstate Monica, Sep 05 '13 at 17:54

score 3 · Accepted Answer · answered Sep 04 '13 at 09:28

You can play with LC_NUMERIC and setlocale() or build your own function, something like:

#include <stdio.h>
#include <stdlib.h>

char *fmt(long x)
{
    char s[64], *p = s, *q, *r;
    int len;

    len = sprintf(p, "%ld", x);
    q = r = malloc(len + (len / 3) + 1);
    if (r == NULL) return NULL;
    if (*p == '-') {
        *q++ = *p++;
        len--;
    }
    switch (len % 3) {
        do {
            *q++ = ',';
            case 0: *q++ = *p++;
            case 2: *q++ = *p++;
            case 1: *q++ = *p++;
        } while (*p);
    }
    *q = '\0';
    return r;
}

int main(void)
{
    char *s = fmt(9876543);

    printf("%s\n", s);
    free(s);
    return 0;
}

+1 Have not found an answer that works for INT_MIN and is portable in "How to format a number from 1123456789 to 1,123,456,789 in C?". This one appears to be both (aside form the magic number 64). — chux - Reinstate Monica, Sep 05 '13 at 18:01

score 0 · Answer 2 · answered Sep 04 '13 at 09:27

0

I believe there is no built-in function for that. However you can convert the integer to string and than compute the comma positions depending on the length of the resulting string(tip:first comma will be after strlen(s)%3 digits, avoid leading comma).

answered Sep 04 '13 at 09:27

Ivaylo Strandjev

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Display an integer comma separated in C?

2 Answers2