Classes

1. Classes

2. Class Definitions: • A class definition starts with the keyword class followed by the class name; and the class body, enclosed by a pair of curly braces. • classBox • { • public: • double length;// Length of a box • double breadth;// Breadth of a box • double height;// Height of a box • };

3. Define C++ Objects: • We declare objects of a class with exactly the same sort of declaration that we declare variables of basic types. • BoxBox1;// Declare Box1 of type Box • BoxBox2;// Declare Box2 of type Box

4. Accessing the Data Members: • The public data members of objects of a class can be accessed using the direct member access operator (.).

5. #include<iostream> • usingnamespace std; • classBox • { • public: • double length;// Length of a box • double breadth;// Breadth of a box • double height;// Height of a box • }; • int main() • { • BoxBox1;// Declare Box1 of type Box • BoxBox2;// Declare Box2 of type Box • double volume =0.0;// Store the volume of a box here • // box 1 specification • Box1.height =5.0; • Box1.length =6.0; • Box1.breadth =7.0; • // box 2 specification • Box2.height =10.0; • Box2.length =12.0; • Box2.breadth =13.0; • // volume of box 1 • volume =Box1.height *Box1.length *Box1.breadth; • cout <<"Volume of Box1 : "<< volume <<endl; • // volume of box 2 • volume =Box2.height *Box2.length *Box2.breadth; • cout <<"Volume of Box2 : "<< volume <<endl; • return0; • }

6. Output: • Volume of Box1:210 • Volume of Box2:1560

7. #include <iostream> • usingnamespace std; • class Rectangle { • int width, height; • public: • void set_values (int,int); • int area () { • return width*height;} • }; • void Rectangle::set_values (int x, int y) { • width = x; • height = y; • } • int main () { • Rectangle rect, rectb; • rect.set_values (3,4); • rectb.set_values (5,6); • cout << "rect area: " << rect.area() << endl; • cout << "rectb area: " << rectb.area() << endl; • return 0; • } • rect area: 12 • rectb area: 30

8. Constructors • Create and initialize new instances of a class • Have the same name as the class • Have no return type, not even void • A default constructor has no arguments • The compiler will generate a default constructor if you do not define any constructors • Destructor • Destroys an instance of an object when the object’s lifetime ends

9. Define class circle with data member radius, and function: • setRadius: function for radius variable. • getRadius: function for return radius value. • getArea: Returns the area of a circle ,area=pi* radius* radius. • getCircumference: Returns the circumference of a circle ,Circumference=2 * pi * radius.

10. Define class Course with data member course_name, course_ID, course_hours and course_Teacher and function set and get for each data members: