CPP Notes

• private and public are keywords.

• These keywords are popularly called access specifiers or visibility modes.

• They control which members of a class are accessible from outside the class and which are not.

• Members declared as public can be accessed from outside the class.

• Members declared as private cannot be accessed from outside the class.

• Normally, we declare data members of a class as private and member functions as public.

• In C++, when we design a class, everything is private by default, so there is no need to explicitly write private.

• To make members accessible from outside, we use the keyword public.

• There is one more keyword called protected, which is also an access specifier, but it is discussed only in the chapter on Inheritance.

#include <iostream>
using namespace std;

class Student {
private:
    int roll;  // private data member
    char grade;  // private data member
    float per;  // private data member

public:
    void getData() { // public member function
        cout << "Enter roll, grade and percentage: ";
        cin >> roll >> grade >> per;
    }

    void showData() { // public member function
        cout << "Roll: " << roll << endl;
        cout << "Grade: " << grade << endl;
        cout << "Percentage: " << per << endl;
    }
};

int main() {
    Student s1;  // object of class

    s1.getData();  // access public member function
    s1.showData(); // access public member function

    return 0;
}

Questiob: Write an object-oriented Cpp program to calculate and print the sum of two integers given by the user.

#include <iostream>
using namespace std;

class Num {
private:
    int a, b, c;   

public:
    void get() {
        cout << "Enter 2 integers: ";
        cin >> a >> b;
    }

    void add() {
        c = a + b;
    }

    void show() {
        cout << "Numbers are " << a << " and " << b << endl;
        cout << "Their sum is " << c << endl;
    }
};

int main() {
    Num obj;      

    obj.get();     
    obj.add();     
    obj.show();    

    return 0;
}