C++ - Calculate Area For Circle, Triangle and Rectangle

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I have given a sample program to calculate the area for Circle, Triangle and Rectangle. This sample code is also an example for the concept of polymorphism.

Source Code

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#include <stdio.h>

#include <iostream>

#include <tchar.h>

#include <math.h>

 

 

class CShape

{

public:

    virtual double CalculateArea() = 0;

};

 

class CTriangle : public CShape

{

    double height;

    double base;

    double area;

 

public:

    CTriangle() : base(12.2), height(18.8)

    {

    }

 

    CTriangle(double b, double h) : base(b), height(h)

    {

    }

 

    void SetHeight(double h) { height = h; }

    void SetBase(double b) { base = b; }

 

    double GetHeight() const { return height; }

    double GetBase() const { return base; }

 

    double CalculateArea()

    {

        area = base / 2 * height;

 

        std::cout << "\nTriangle\nInput: Base = " << base << " Height = " << height << "\n";

        std::cout << "Output: Area = ";

        std::cout.width(8);

        std::cout.precision(4);

        std::cout.fill('*');

        std::cout << area;

        std::cout << "\n";

 

        return area;

    }

};

 

class CRectangle : public CShape

{

    double length;

    double width;

 

    double area;

 

public:

    CRectangle(double l, double w) : length(l), width(w)

    {

    }

 

    CRectangle() : length(26.6), width(15.8)

    {

    }

 

    void SetLength(double l) { length = l; }

    void SetWidth(double w) { width = w; }

 

    double GetLength() const { return length; }

    double GetWidth() const { return width; }

 

    double CalculateArea()

    {

        area = length * width;

 

        std::cout << "\nRectangle\nInput: Length = " << length << " width = " << width << "\n";

        std::cout << "Output: Area = ";

        std::cout.width(8);

        std::cout.precision(4);

        std::cout.fill('*');

        std::cout << area;

        std::cout << "\n";

 

        return area;

    }

 

};

 

class CCircle : public CShape

{

    double radius;

    double area;

 

public:

    CCircle(double r = 6.8) : radius(r) { };

 

    void SetRadius(double r) { radius = r; }

    double GetRadius() const { return radius; }

 

    double CalculateArea()

    {

        area = 3.14159265 * radius * radius;

 

        std::cout << "\nCircle\nInput: Radius = " << radius << "\n";

        std::cout << "Output: Area = ";

        std::cout.width(8);

        std::cout.precision(4);

        std::cout.fill('*');

        std::cout << area;

        std::cout << "\n";

 

        return area;

    }

 

};

 

void main()

{

    CRectangle *shapeRect = new CRectangle();

    CCircle *shapeCircle = new CCircle();

    CTriangle *shapeTriangle = new CTriangle();

 

    CShape *shapeArea[] =  { shapeRect, shapeCircle, shapeTriangle };

 

    for(int i = 0; i < sizeof(shapeArea) / sizeof(shapeArea[0]); i++)

        shapeArea[i]->CalculateArea();

 

    shapeRect->SetLength(16.8);

    shapeRect->SetWidth(8.8);

    shapeCircle->SetRadius(13.8);

    shapeTriangle->SetBase(2.5);

    shapeTriangle->SetHeight(3.8);

 

    for(int i = 0; i < sizeof(shapeArea) / sizeof(shapeArea[0]); i++)

        shapeArea[i]->CalculateArea();

 

 

    delete shapeRect;

    delete shapeCircle;

    delete shapeTriangle;

}

 

Output

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