variadic function in c

// C program to demonstrate working of  
// variable arguments to find average 
// of multiple numbers. 
#include <stdarg.h> 
#include <stdio.h> 
  
int average(int num, ...) 
{ 
    va_list valist; 
  
    int sum = 0, i; 
  
    va_start(valist, num); 
    for (i = 0; i < num; i++)  
        sum += va_arg(valist, int); 
  
    va_end(valist); 
  
    return sum / num; 
} 
  
// Driver code 
int main() 
{ 
    printf("Average of {2, 3, 4} = %d\n", 
                         average(2, 3, 4)); 
    printf("Average of {3, 5, 10, 15} = %d\n", 
                      average(3, 5, 10, 15)); 
    return 0; 
}