C++ Program To Make Geometry Calculator Using Switch Case

In this article, you will learn how to create a basic geometry calculator program in C++ using the switch case statement, allowing users to calculate properties of different shapes.

Problem Statement

Many applications require quick calculations of geometric properties like area and perimeter for various shapes. Manually performing these calculations can be error-prone and time-consuming. There is a need for a simple, interactive tool that can automate these common geometric computations.

Example

Imagine a user wants to find the area of a circle with a radius of 5 units. A geometry calculator would prompt for the shape, then the dimensions, and output:

Enter radius of the circle: 5
Area of Circle: 78.5398
Circumference of Circle: 31.4159

Background & Knowledge Prerequisites

To understand and implement the geometry calculator, readers should be familiar with:

• C++ Basics: Understanding of fundamental data types (e.g., int, double), variable declaration, and basic input/output operations (cin, cout).
• Conditional Statements: Knowledge of if-else statements.
• Looping Constructs: Familiarity with while or do-while loops for repeating actions.
• Switch Case Statement: How to use switch for multi-way branching based on a variable's value.
• Mathematical Operations: Basic arithmetic operators (+, -, *, /) and potentially the cmath library for constants like PI or functions like pow().

Use Cases or Case Studies

A geometry calculator can be incredibly useful in several scenarios:

• Education: Students can use it to verify their homework answers for math and physics problems involving shapes.
• Engineering and Architecture: Engineers might use it for quick estimations of material requirements based on area (e.g., paint, flooring) or perimeter (e.g., fencing).
• Game Development: Calculating collision boundaries or rendering areas for in-game objects often involves geometric formulas.
• DIY Projects: Homeowners or hobbyists can use it to determine quantities for projects like building a garden bed (perimeter) or tiling a floor (area).
• Robotics: Path planning and object interaction in robotics often rely on understanding the geometry of the environment.

Solution Approaches

We will implement a geometry calculator focusing on using the switch statement to handle different shape choices. This approach provides a clear and structured way to manage multiple calculation options.

Approach 1: Menu-Driven Calculator with Switch Case

This approach involves presenting a menu of shapes to the user. Based on the user's selection, a switch statement directs the program to the appropriate code block for calculating the properties of that specific shape. A loop will allow the user to perform multiple calculations until they choose to exit.

• One-line summary: Create an interactive, menu-driven C++ program to calculate area and perimeter/circumference for various shapes using a switch statement for shape selection.

• Code example:

// 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;
}

Run

• Sample output:

Welcome to the Geometry Calculator!

-------------------------------------
Select a shape to calculate properties:
1. Circle
2. Rectangle
3. Triangle (Area only)
4. Exit
Enter your choice (1-4): 1

Enter radius of the circle: 7
Area of Circle: 153.938
Circumference of Circle: 43.9823

-------------------------------------
Select a shape to calculate properties:
1. Circle
2. Rectangle
3. Triangle (Area only)
4. Exit
Enter your choice (1-4): 2

Enter length of the rectangle: 10
Enter width of the rectangle: 5
Area of Rectangle: 50
Perimeter of Rectangle: 30

-------------------------------------
Select a shape to calculate properties:
1. Circle
2. Rectangle
3. Triangle (Area only)
4. Exit
Enter your choice (1-4): 5

Invalid choice. Please enter a number between 1 and 4.

-------------------------------------
Select a shape to calculate properties:
1. Circle
2. Rectangle
3. Triangle (Area only)
4. Exit
Enter your choice (1-4): 4

Exiting Geometry Calculator. Goodbye!

• Stepwise explanation:

1. Include Headers: iostream is included for input/output operations, and cmath for the M_PI constant (or define M_PI manually if needed) and potential mathematical functions.
2. Variables Declaration: choice (integer) stores the user's menu selection. radius, length, width, base, and height (double) store the dimensions for calculations to allow for decimal values.
3. Main Loop: A do-while loop is used to repeatedly display the menu and process user input until the user decides to exit (by entering '4').
4. Display Menu: Inside the loop, the program prints a list of options (Circle, Rectangle, Triangle, Exit) to the console.
5. Get User Choice: It prompts the user to enter their choice and reads the input into the choice variable.
6. switch Statement: The switch(choice) statement evaluates the user's input:
   • case 1 (Circle): Prompts for the radius, performs a basic check for negative input, then calculates and prints the area (M_PI * radius * radius) and circumference (2 * M_PI * radius).

1. break Statements: Each case block ends with a break statement to exit the switch and prevent "fall-through" to the next case.
2. Loop Termination: The do-while loop continues as long as choice is not 4. Once choice is 4, the loop terminates, and the program ends.

Conclusion

Creating a geometry calculator using the switch statement in C++ offers an intuitive and organized way to handle multiple calculation options. This approach allows for clear separation of concerns for different shapes, making the code readable and easy to maintain. By incorporating a loop, the program provides a continuous, interactive experience for the user.

Summary

• A geometry calculator automates common geometric computations, reducing errors and saving time.
• Prerequisites: Basic C++ knowledge, including variables, cin/cout, do-while loops, and switch statements.
• Implementation: A menu-driven system utilizing a do-while loop for repeated calculations and a switch statement to direct flow based on the user's chosen shape.
• Structure: Each case within the switch handles a specific shape's input and calculation, promoting modularity.
• Benefits: Provides an interactive, user-friendly tool for students, engineers, and hobbyists alike for quick geometric property calculations.