A.2.3 Example of a Variadic Function

Here is a complete sample function that accepts a variable number of arguments. The first argument to the function is the count of remaining arguments, which are added up and the result returned. While trivial, this function is sufficient to illustrate how to use the variable arguments facility.

     #include <stdarg.h>
     #include <stdio.h>
     
     int
     add_em_up (int count,...)
     {
       va_list ap;
       int i, sum;
     
       va_start (ap, count);         /* Initialize the argument list. */
     
       sum = 0;
       for (i = 0; i < count; i++)
         sum += va_arg (ap, int);    /* Get the next argument value. */
     
       va_end (ap);                  /* Clean up. */
       return sum;
     }
     
     int
     main (void)
     {
       /* This call prints 16. */
       printf ("%d\n", add_em_up (3, 5, 5, 6));
     
       /* This call prints 55. */
       printf ("%d\n", add_em_up (10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
     
       return 0;
     }