Functions with a Variable Number of Arguments - C Function

C examples for Function:Variable Length Argument

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Description

Functions with a Variable Number of Arguments

Demo Code

#include <stdio.h>
#include <stdarg.h>

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

int main(void){
  double v1 = 10.5, v2 = 2.5;
  int num1 = 6, num2 = 5;
  long num3 = 12L, num4 = 20L;

  printf("Average = %.2lf\n", average(v1, 3.5, v2, 4.5, 0.0));
  printf("Average = %.2lf\n", average(1.0, 2.0, 0.0));
  printf("Average = %.2lf\n", average( (double)num2, v2,(double)num1,
                                      (double)num4,(double)num3, 0.0));
  return 0;//  ww  w.  j  a va 2s  .c om
}

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 = 0.0;                            // 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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