/*
Beginning C: From Novice to Professional, Fourth Edition
By Ivor Horton
ISBN: 1-59059-735-4
640 pp.
Published: Oct 2006
*/
#include <stdio.h>
#include <stdarg.h>
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;
}