Static members

#include <iostream>
using namespace std;

class Circle {
  double radius;
public:
  Circle (double);
  double area (void) {return (3.141593*radius*radius);}
  static int count; 
};

Circle::Circle( double r)
{
  radius = r; 
  count++; 
  return; 
};

int Circle::count = 0;

int main () {
  Circle crcla(3);
  Circle crclb(4);
  cout << "crcla area " << crcla.area() << endl;
  cout << "count " << Circle::count << endl;
  return 0;
}