Question

Write a program to calculate the area of circle, rectangle using a class. The program would prompt a user to select (1) circle or (2) rectangle followed by asking the necessary dimensions. Once the user enters the valid input, the program then calculates the area and prints the final value. The set()/get() methods must include data validation.

Answer 1

Answer:

The following program written in c++:

#include <iostream>

using namespace std;

class Circle   //define class

{

private :      //access modifier

double pi, radius, area;    // set double type variables

public :

Circle (double radius = 0.0)    //define constructor

{

pi = 3.1415;

this->radius = radius;

}

void setRadius (double radius)     // define void type method

{

if (radius < 0){      // if the radius is negative don't take it

cout << "Radius can't be negative." << endl;

return;

}

this->radius = radius;

}

double getArea ()        // define double type method

{

area = pi * radius * radius;

return area;

}

};

class Rectangle      //define class

{

private:       //access modifier

double length ,breadth ,area; // set double type private data types

public:

Rectangle (double length = 0.0, double breadth = 0.0) // define constructor

{

this->length = length;

this->breadth = breadth;

}

void setDimension (double length , double breadth ) // define void type method

{

if (length < 0 || breadth < 0){ //set if condition, if the dimensions is negative than don't take it

cout << "Dimensions can't be negative." << endl;

return;

}

this->length = length;

this->breadth = breadth;

}

double getArea ()      // define double type method

{

area = length * breadth;

return area;

}

};

int main()      //main function

{

int choice;      //integer type variable

double radius, length, breadth;

Circle c;

Rectangle r;

cout << "Select ( 1 ) Circle or select ( 2 ) Rectangle : "; // get the choice of user

cin >> choice;

switch (choice)

{

case 1 : cout << "Enter radius of circle : ";

cin >> radius;

c.setRadius(radius);

cout << "Area of circle is : " << c.getArea();

break;

case 2 : cout << "Enter dimensions of rectangle : ";

cin >> length >> breadth;

r.setDimension(length,breadth);

cout << "Area of rectangle is : " << r.getArea();

break;

default : cout << "Invalid Selection...";

}

return 0;

}

Explanation:

Here, we define two classes "Circle" and "Rectangle"

Then, we create first two function which get the value from the user.

Then, we create the second two functions which return the calculation of the following formulas.