#include <cstdarg>
#include <iostream>

using namespace std;

double average ( int num, ... )
{
  va_list arguments;                     
  double sum = 0;

  va_start ( arguments, num );          
  for ( int x = 0; x < num; x++ )        
    sum += va_arg ( arguments, double ); 
  va_end ( arguments );                 

  return sum / num;                      
}
int main()
{
  cout<< average ( 3, 12.2, 22.3, 4.5 ) <<endl;
  cout<< average ( 5, 3.3, 2.2, 1.1, 5.5, 3.3 ) <<endl;
  cin.get();
}

#include <vector>
#include <iostream>

template<typename T>
class average
{
public:
	average(T in, T null_in = 0) : null(null_in) 
		{ nums.push_back(in); }
	const T null;
	average & operator()(T n) 
		{ nums.push_back(n); return *this; }
	long double value()
	{
		T sum = null;
		for(std::size_t i = 0; i < nums.size(); ++i)
			sum += nums[i];
		return (long double)sum / (long double)nums.size();
	}
private:
	std::vector<T> nums;
};

template<typename T>
average<T> avg(T first)
{
	return average<T>(first);
}

template<typename T>
std::ostream & operator << (std::ostream & s, average<T> & a)
{
	s << a.value();
	return s;
}

int main(int argc, char* argv[])
{
	std::cout << avg(3)(22.3345)(76)(2) << std::endl; //bad: 22.3345 will be added as 22
	std::cout << avg(22.3345)(3)(76)(2) << std::endl; //good: this is what you want.
        //Incidentally, you could just implement it as a double, without the templates.
	return 0;
}

#include <numeric>
#include <cstddef>
#include <iostream>

int main()
{
    double numbers[] = {5, 3.3, 2.2, 1.1, 5.5, 3.3};
    const std::size_t size = sizeof(numbers) / sizeof(numbers[0]);
    double average = std::accumulate(numbers, numbers + size, 0.0) / size;
    std::cout << average << std::endl;
}

#include <iostream>

using namespace std;

int mult (int x, int y);

int main ()
{
    int x;
    int y;
    
    cout<<"Please input two numbers to be multiplied, after inserting the first number, press enter. Then input the second number and press enter: ";
    cin>> x >> y;
    cin.ignore ();
    cout<<"The product of you two numbers is " << x * y <<"\n";
    cin.get ();
}

int mult ( int x, int y )
{
    return x * y;
}