private.cpp

// c++ oop private access modifier

#include <iostream>

using namespace std;

// defining a class
class Circle {
    private:                     // we defined that this class data members will be private
        double radius;
    
    public:                     // and we kept the member function public
        double compute_area(double r){    
            radius = r;         // member function can access private data member radius
            
            double area = 3.14*radius*radius;
            
            cout << "Radius is: " << radius << endl;
            cout << "Area is: " << area;
        }
};                              // always put semicolons after defining a class

//main function
int main(){
    Circle ball;                // create a object called ball
    
    ball.compute_area(3.5);     // trying to access private data member radius directly from outside the class

    return 0;
}