Aim

Write a C++ program to declare a class. Declare pointer to class. Initialize and display the contents of the class member.

Procedure

• Step 1 - Include the required header files (iostream.h, conio.h, and windows.h for colors).
• Step 2 - Create a class (Rectangle) with the following members as public members.
  • length and breadth as data members.
  • initialize(), getArea() and display() as member functions.
• Step 3 - Create a main() method.
• Step 4 - Create a variable (rect) and a pointer variable (class_ptr) of the above class inside the main() method.
• Step 5 - Assign the address of class object (rect) to class pointer object (class_ptr).
• Step 6 - Then, call the member functions initialize() and display() using class pointer object (class_ptr) to illustrate member functions access using class pointer.
• Step 7 - Assign values to data members of the class using class pointer object to illustrate data members access using class pointer.
• Step 8 - Finally, call the member functions initialize() and display() using class pointer object (class_ptr).

Implementation

#include <windows.h>
#include <iostream>

using namespace std;

class RectangleTest{

    public:
        int length, breadth;

    public:
        void initialize(int len, int bre){
            length = len;
            breadth = bre;
        }
        int getArea(){
            return 2*length*breadth;
        }
        void display(){
            int area = getArea();
            cout<<"\n*** Rectangle Information ***\n";
            cout<<"Length = "<<length;
            cout<<"\nBreadth = "<<breadth;
            cout<<"\nArea = "<<area;
            cout<<"\n-----------------------------\n";
        }

};

int main()
{
    RectangleTest rect, *class_ptr;
    HANDLE color=GetStdHandle(STD_OUTPUT_HANDLE);
    class_ptr = &rect;

    //Accessing member functions using class pointer
    SetConsoleTextAttribute(color, 10 );    //Setting color Green
    cout<<"\nUsing member functions access";
    SetConsoleTextAttribute(color, 7 );     //Setting color White
    class_ptr->initialize(10,5);
    class_ptr->display();

    //Accessing data members using class pointer
    SetConsoleTextAttribute(color, 10 );    //Setting color Green
    cout<<"\nUsing data members access";
    SetConsoleTextAttribute(color, 7 );     //Setting color White
    class_ptr->length = 2;
    class_ptr->breadth = 3;
    class_ptr->initialize(class_ptr->length,class_ptr->breadth);
    class_ptr->display();

    return 0;
}

Result