Const variables inside a class definition

NOTE : -

THIS CONTENT IS NOT ORIGINAL

25. Const variables inside a class definition

A class variable can also be constant. That's just like static, except it is given a value inside the class declaration and that value cannot be modified:

using namespace std;
#include 

class vector
{
public:

  double x;
  double y;
  const static double pi = 3.1415927;

  vector (double a = 0, double b = 0)
  {
     x = a;
     y = b;
  }

  double cilinder_volume ()
  {
     return x * x / 4 * pi * y;
  }
};

int main()
{
  cout << "The value of pi: " << vector::pi << endl << endl;

  vector k (3, 4);

  cout << "Result: " << k.cilinder_volume() << endl;

  return 0;
}

Output

The value of pi: 3.14159 Result: 28.2743

BIBILOGRAPHY / REFERENCE : - http://www.4p8.com/eric.brasseur/cppcen.html