Shape Calculator in C++

Last Updated : 20 Jun, 2025

Shape Calculator is a console-based C++ application that demonstrates advanced OOP concepts through a system of shapes (e.g., Circle, Rectangle, Triangle, Square, Ellipse).

Features

Our Shape Calculator provides the following features:

Create different shapes at runtime (Circle, Rectangle, Square, Triangle, Ellipse)
Display area and perimeter
Compare two shapes by area
Menu-driven dashboard

Project Requirements

The following C++ concepts are required:

Classes, Objects, Inheritance
Access Specifiers, Constructors, Destructors
Virtual Functions, Method Overriding
Operator Overloading
Dynamic Memory Allocation

You’ll need a working C++ environment that consists of compiler like g++, clang++, or IDE like Code::Blocks, Visual Studio Code.

Implementation

Let’s break the implementation into steps:

STEP 1: Base Shape Class

We define a Shape class with virtual functions for area, perimeter, and displaying info.

C++

#include <bits/stdc++.h> using namespace std; class Shape { public:  virtual double area() const = 0;  virtual double perimeter() const = 0;  virtual void display() const = 0;  // Virtual destructor for polymorphism  virtual ~Shape() {}    // Overload > operator to compare areas  bool operator>(const Shape& other) const {  return this->area() > other.area();  } };

STEP 2: Derived Shape Classes

Creating the derived class from the above base class shape:

C++

class Circle : public Shape {  double radius; public:  Circle(double r) : radius(r) {}  double area() const override {  return M_PI * radius * radius;  }  double perimeter() const override {  return 2 * M_PI * radius;  }  void display() const override {  cout << "Circle: radius = " << radius << "\n";  cout << "Area = " << area() << "\n";  cout << "Perimeter = " << perimeter() << "\n";  } }; class Rectangle : public Shape {  double width, height; public:  Rectangle(double w, double h) : width(w), height(h) {}  double area() const override {  return width * height;  }  double perimeter() const override {  return 2 * (width + height);  }  void display() const override {  cout << "Rectangle: width = " << width  << ", height = " << height << "\n";  cout << "Area = " << area() << "\n";  cout << "Perimeter = " << perimeter() << "\n";  } }; class Square : public Rectangle { public:  Square(double side) : Rectangle(side, side) {}  void display() const override {  cout << "Square: side = " << area() << "\n";  Rectangle::display();  } }; class Triangle : public Shape {  double a, b, c; public:  Triangle(double x, double y, double z) : a(x), b(y), c(z) {}  double area() const override {  double s = perimeter() / 2;  return sqrt(s * (s - a) * (s - b) * (s - c));  }  double perimeter() const override {  return a + b + c;  }  void display() const override {  cout << "Triangle: sides = " << a  << ", " << b << ", " << c << "\n";  cout << "Area = " << area() << "\n";  cout << "Perimeter = " << perimeter() << "\n";  } }; class Ellipse : public Shape {  double a, b; public:  Ellipse(double x, double y) : a(x), b(y) {}  double area() const override {  return M_PI * a * b;  }  double perimeter() const override {  return M_PI * (3*(a + b) - sqrt((3*a + b)*(a + 3*b)));  }  void display() const override {  cout << "Ellipse: axes = " << a << ", " << b << "\n";  cout << "Area = " << area() << "\n";  cout << "Perimeter = " << perimeter() << "\n";  } };

STEP 3: Input and Dashboard

This dashboard provides interactive access to the program for creating different shapes depending on the choice of the user.

C++

vector<Shape*> shapes; void createCircle() {  double r;  cout << "Enter radius: ";  cin >> r;  shapes.push_back(new Circle(r)); } void createRectangle() {  double w, h;  cout << "Enter width and height: ";  cin >> w >> h;  shapes.push_back(new Rectangle(w, h)); } void createSquare() {  double s;  cout << "Enter side: ";  cin >> s;  shapes.push_back(new Square(s)); } void createTriangle() {  double a, b, c;  cout << "Enter sides a, b, c: ";  cin >> a >> b >> c;  shapes.push_back(new Triangle(a, b, c)); } void createEllipse() {  double a, b;  cout << "Enter axes a and b: ";  cin >> a >> b;  shapes.push_back(new Ellipse(a, b)); } void displayAllShapes() {  if (shapes.empty()) {  cout << "No shapes created.\n";  return;  }  for (size_t i = 0; i < shapes.size(); i++) {  cout << "\nShape #" << i+1 << ":\n";  shapes[i]->display();  } } void compareShapes() {  if (shapes.size() < 2) {  cout << "Need at least 2 shapes.\n";  return;  }  int i, j;  cout << "Enter indices of shapes (1-based): ";  cin >> i >> j;  if (i < 1 || j < 1 || i > (int)shapes.size() || j > (int)shapes.size()) {  cout << "Invalid indices.\n";  return;  }  if (*shapes[i-1] > *shapes[j-1])  cout << "Shape #" << i << " has larger area.\n";  else  cout << "Shape #" << j << " has larger or equal area.\n"; } void shapeDashboard() {  int choice;  while (true) {  cout << "\n--- Shape Calculator Menu ---\n";  cout << "1. Create Circle\n";  cout << "2. Create Rectangle\n";  cout << "3. Create Square\n";  cout << "4. Create Triangle\n";  cout << "5. Create Ellipse\n";  cout << "6. Display All Shapes\n";  cout << "7. Compare Two Shapes\n";  cout << "8. Exit\n";  cout << "Enter your choice: ";  cin >> choice;  switch (choice) {  case 1: createCircle(); break;  case 2: createRectangle(); break;  case 3: createSquare(); break;  case 4: createTriangle(); break;  case 5: createEllipse(); break;  case 6: displayAllShapes(); break;  case 7: compareShapes(); break;  case 8:  cout << "Exiting Shape Calculator.\n";  return;  default:  cout << "Invalid choice.\n";  }  } }

STEP 4: Main Function

The main function from where everything starts:

C++

int main() { shapeDashboard(); // Cleanup for (Shape* s : shapes) delete s; return 0; }

Execution

Combining all the above components, we get the executable source code:

C++

// Source code #include <bits/stdc++.h> using namespace std; class Shape { public:  virtual double area() const = 0;  virtual double perimeter() const = 0;  virtual void display() const = 0;  virtual ~Shape() {}  // Compare shapes by area  bool operator>(const Shape& other) const {  return this->area() > other.area();  } }; class Circle : public Shape {  double radius; public:  Circle(double r) : radius(r) {}  double area() const override {  return M_PI * radius * radius;  }  double perimeter() const override {  return 2 * M_PI * radius;  }  void display() const override {  cout << "Circle: radius = " << radius << "\n";  cout << "Area = " << area() << "\n";  cout << "Perimeter = " << perimeter() << "\n";  } }; class Rectangle : public Shape {  double width, height; public:  Rectangle(double w, double h) : width(w), height(h) {}  double area() const override {  return width * height;  }  double perimeter() const override {  return 2 * (width + height);  }  void display() const override {  cout << "Rectangle: width = " << width  << ", height = " << height << "\n";  cout << "Area = " << area() << "\n";  cout << "Perimeter = " << perimeter() << "\n";  } }; class Square : public Rectangle { public:  Square(double side) : Rectangle(side, side) {}  void display() const override {  cout << "Square: side = " << area() << "\n";  Rectangle::display();  } }; class Triangle : public Shape {  double a, b, c; public:  Triangle(double x, double y, double z) : a(x), b(y), c(z) {}  double area() const override {  double s = perimeter() / 2;  return sqrt(s * (s - a) * (s - b) * (s - c));  }  double perimeter() const override {  return a + b + c;  }  void display() const override {  cout << "Triangle: sides = " << a  << ", " << b << ", " << c << "\n";  cout << "Area = " << area() << "\n";  cout << "Perimeter = " << perimeter() << "\n";  } }; class Ellipse : public Shape {  double a, b; public:  Ellipse(double x, double y) : a(x), b(y) {}  double area() const override {  return M_PI * a * b;  }  double perimeter() const override {  return M_PI * (3*(a + b) - sqrt((3*a + b)*(a + 3*b)));  }  void display() const override {  cout << "Ellipse: axes = " << a << ", " << b << "\n";  cout << "Area = " << area() << "\n";  cout << "Perimeter = " << perimeter() << "\n";  } }; vector<Shape*> shapes; void createCircle() {  double r;  cout << "Enter radius: ";  cin >> r;  shapes.push_back(new Circle(r)); } void createRectangle() {  double w, h;  cout << "Enter width and height: ";  cin >> w >> h;  shapes.push_back(new Rectangle(w, h)); } void createSquare() {  double s;  cout << "Enter side: ";  cin >> s;  shapes.push_back(new Square(s)); } void createTriangle() {  double a, b, c;  cout << "Enter sides a, b, c: ";  cin >> a >> b >> c;  shapes.push_back(new Triangle(a, b, c)); } void createEllipse() {  double a, b;  cout << "Enter axes a and b: ";  cin >> a >> b;  shapes.push_back(new Ellipse(a, b)); } void displayAllShapes() {  if (shapes.empty()) {  cout << "No shapes created.\n";  return;  }  for (size_t i = 0; i < shapes.size(); i++) {  cout << "\nShape #" << i+1 << ":\n";  shapes[i]->display();  } } void compareShapes() {  if (shapes.size() < 2) {  cout << "Need at least 2 shapes.\n";  return;  }  int i, j;  cout << "Enter indices of shapes (1-based): ";  cin >> i >> j;  if (i < 1 || j < 1 || i > (int)shapes.size() || j > (int)shapes.size()) {  cout << "Invalid indices.\n";  return;  }  if (*shapes[i-1] > *shapes[j-1])  cout << "Shape #" << i << " has larger area.\n";  else  cout << "Shape #" << j << " has larger or equal area.\n"; } void shapeDashboard() {  int choice;  while (true) {  cout << "\n--- Shape Calculator Menu ---\n";  cout << "1. Create Circle\n";  cout << "2. Create Rectangle\n";  cout << "3. Create Square\n";  cout << "4. Create Triangle\n";  cout << "5. Create Ellipse\n";  cout << "6. Display All Shapes\n";  cout << "7. Compare Two Shapes\n";  cout << "8. Exit\n";  cout << "Enter your choice: ";  cin >> choice;  switch (choice) {  case 1: createCircle(); break;  case 2: createRectangle(); break;  case 3: createSquare(); break;  case 4: createTriangle(); break;  case 5: createEllipse(); break;  case 6: displayAllShapes(); break;  case 7: compareShapes(); break;  case 8:  cout << "Exiting Shape Calculator.\n";  return;  default:  cout << "Invalid choice.\n";  }  } } int main() {  shapeDashboard();  // Cleanup  for (Shape* s : shapes)  delete s;  return 0; }