va_arg c example

va_arg.c

#include <stdio.h>
#include <stdarg.h>

int sum(int argc, ...)
{
    int res = 0;

    va_list ap;
    va_start(ap, argc);

    for (int i = 0; i < argc; i++) {
        res += va_arg(ap, int);
    }

    va_end(ap);

    return res;
}

int main(void)
{
    fprintf(stderr, "%d\n", sum(4, 1, 2, 3, 4));

    return 0;
}