#include <iostream>
#include <iomanip>
#include <cstdarg>

using namespace std;

struct thing
{
  int num;

  thing(int n, ...)
  { num = n;
    cout << "constructor, n = " << n << "\n";
    va_list params;
    va_start(params, n);
    for (int i = 0; i < n; i += 1)
      cout << "  arg " << i << " = " << va_arg(params, int) << "\n";
    va_end(params); }

  void mmm(int x, ...)
  { cout << "method mmm\n";
    va_list params;
    va_start(params, x);
    for (int i = 0; i < num; i += 1)
      cout << "  arg " << i << " = " << va_arg(params, int) << "\n";
    va_end(params); }

  void operator()(int x, ...)
  { cout << "operator()\n";
    va_list params;
    va_start(params, x);
    for (int i = 0; i < num; i += 1)
      cout << "  arg " << i << " = " << va_arg(params, int) << "\n";
    va_end(params); } };

double avg(int n, ...)
{ double sum = 0.0;
  cout << "ordinary function, n = " << n << "\n";
  va_list params;  
  va_start(params, n);  
  for (int i = 0; i < n; i += 1)  
  { double val = va_arg(params, double);
    cout << "  arg " << i << " = " << val << "\n";
    sum += val; }
  va_end(params);    
  if (n > 0)  
    return sum / n;  
  else  
    return 0; }

int main()
{ 
  thing a(3, 99, 88, 77);
  a.mmm(11, 22, 33);
  a(10101, 20202, 30303);
  cout << "average = " << avg(4, 2, 3, 4, 5) << "\n";
}