C库宏 va_start()

#include<stdarg.h>

#include<stdio.h>



int sum(int, ...);



int main(void) {

   printf("Sum of 10, 20 and 30 = %d\n",  sum(3, 10, 20, 30) );

   printf("Sum of 4, 20, 25 and 30 = %d\n",  sum(4, 4, 20, 25, 30) );



   return 0;

}



int sum(int num_args, ...) {

   int val = 0;

   va_list ap;

   int i;



   va_start(ap, num_args);

   for(i = 0; i < num_args; i++) {

      val += va_arg(ap, int);

   }

   va_end(ap);



   return val;

}