truncate.c

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

int main(int argc, char *argv[])
{
    char* buf;
    asprintf(&buf, "%s", ", this is some butts,     ");
    char* end = &buf[sizeof(char) * strlen(buf) -1];


    while (*end == ' ' || *end == ',') {
        *end = '\0';
        end--;
    }

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