Example: Geometry Calculator using Switch Case in C++

// Geometry Calculator using Switch Case
#include <iostream>
#include <cmath> // Required for M_PI and pow()

// Define PI if M_PI is not consistently available or for custom precision
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif

using namespace std;

int main() {
    int choice;
    double radius, length, width, base, height;
    
    // Step 1: Display a welcome message and the main menu
    cout << "Welcome to the Geometry Calculator!" << endl;
    
    do {
        cout << "\n-------------------------------------" << endl;
        cout << "Select a shape to calculate properties:" << endl;
        cout << "1. Circle" << endl;
        cout << "2. Rectangle" << endl;
        cout << "3. Triangle (Area only)" << endl;
        cout << "4. Exit" << endl;
        cout << "Enter your choice (1-4): ";
        cin >> choice;

        // Step 2: Use a switch statement to handle user's choice
        switch (choice) {
            case 1: // Circle
                cout << "\nEnter radius of the circle: ";
                cin >> radius;
                if (radius < 0) {
                    cout << "Radius cannot be negative. Please try again." << endl;
                    break;
                }
                cout << "Area of Circle: " << M_PI * radius * radius << endl;
                cout << "Circumference of Circle: " << 2 * M_PI * radius << endl;
                break;
            case 2: // Rectangle
                cout << "\nEnter length of the rectangle: ";
                cin >> length;
                cout << "Enter width of the rectangle: ";
                cin >> width;
                if (length < 0 || width < 0) {
                    cout << "Length and width cannot be negative. Please try again." << endl;
                    break;
                }
                cout << "Area of Rectangle: " << length * width << endl;
                cout << "Perimeter of Rectangle: " << 2 * (length + width) << endl;
                break;
            case 3: // Triangle (Area only for simplicity)
                cout << "\nEnter base of the triangle: ";
                cin >> base;
                cout << "Enter height of the triangle: ";
                cin >> height;
                if (base < 0 || height < 0) {
                    cout << "Base and height cannot be negative. Please try again." << endl;
                    break;
                }
                cout << "Area of Triangle: " << 0.5 * base * height << endl;
                // Perimeter requires three sides, which adds complexity for a simple example.
                // For now, we focus on area using base and height.
                break;
            case 4: // Exit
                cout << "\nExiting Geometry Calculator. Goodbye!" << endl;
                break;
            default: // Invalid choice
                cout << "\nInvalid choice. Please enter a number between 1 and 4." << endl;
                break;
        }
    } while (choice != 4); // Step 3: Loop until user chooses to exit

    return 0;
}