Program:

// program to convert angle in degree to radian
// conversion routine is in source

#include<iostream>
using namespace std;
#define PI 3.1416

class Radian{
	private:
		float radian;
	public:
		Radian(float r = 0){
			radian = r;
		}
		void display(){
			cout<<"Value in Radian:"<<radian<<endl;
		}

};

class Degree{
	private:
		float degree;
	public:
		Degree(float d = 0){
			degree = d;
		}
		// conversion routine in source
		operator Radian(){
			return Radian(degree * PI / 180.0);
		}
		void display(){
			cout<<"Value in Degree:"<<degree<<endl;
		}
};


int main(){
	Degree deg(360);
	Radian rad;
	rad = deg;
	deg.display();
	rad.display();
	return 0;
}

Sample Run:

Value in Degree:360
Value in Radian:6.2832