Calculating an average using variable argument lists in C

Calculating an average using variable argument lists in C

#include 
#include 
double average(double v1 , double v2,...);       /* Function prototype */

int main(void)
{
 double Val1 = 10.5, Val2 = 2.5;
 int num1 = 6, num2 = 5;
 long num3 = 12, num4 = 20;
 printf("\n Average = %lf", average(Val1, 3.5, Val2, 4.5, 0.0));
 printf("\n Average = %lf", average(1.0, 2.0, 0.0));
 printf("\n Average = %lf\n", average( (double)num2, Val2,(double)num1,
 (double)num4,(double)num3, 0.0));
 return 0;
}

/* Function to calculate the average of a variable number of arguments */
double average( double v1, double v2,...)
{
 va_list parg;              /* Pointer for variable argument list */
 double sum = v1+v2;        /* Accumulate sum of the arguments    */
 double value = 0;          /* Argument value                     */
 int count = 2;             /* Count of number of arguments       */

 va_start(parg,v2);         /* Initialize argument pointer        */

 while((value = va_arg(parg, double)) != 0.0)
 {
   sum += value;
   count++;
 }
 va_end(parg);              /* End variable argument process      */
 return sum/count;
}

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