C++/Application Programs/Program

Menu Driven Program

Menu Driven Program in C++ (3 Ways With Output)

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#include <iostream>
using namespace std;

void displayMenu() {
    cout << "\n=== MENU ===" << endl;
    cout << "1. Add" << endl;
    cout << "2. Subtract" << endl;
    cout << "3. Multiply" << endl;
    cout << "4. Divide" << endl;
    cout << "5. Exit" << endl;
    cout << "Enter your choice: ";
}

int main() {
    int choice;
    double num1, num2, result;
    
    do {
        displayMenu();
        cin >> choice;
        
        if (choice >= 1 && choice <= 4) {
            cout << "Enter two numbers: ";
            cin >> num1 >> num2;
        }
        
        switch(choice) {
            case 1:
                result = num1 + num2;
                cout << "Result: " << result << endl;
                break;
            case 2:
                result = num1 - num2;
                cout << "Result: " << result << endl;
                break;
            case 3:
                result = num1 * num2;
                cout << "Result: " << result << endl;
                break;
            case 4:
                if (num2 != 0) {
                    result = num1 / num2;
                    cout << "Result: " << result << endl;
                } else {
                    cout << "Error: Division by zero!" << endl;
                }
                break;
            case 5:
                cout << "Exiting..." << endl;
                break;
            default:
                cout << "Invalid choice!" << endl;
        }
    } while(choice != 5);
    
    return 0;
}

Output

=== MENU ===
1. Add
2. Subtract
3. Multiply
4. Divide
5. Exit
Enter your choice: 1
Enter two numbers: 10 20
Result: 30

=== MENU ===
1. Add
2. Subtract
3. Multiply
4. Divide
5. Exit
Enter your choice: 5
Exiting...

This program teaches you how to create a menu-driven program in C++. A menu-driven program provides a user-friendly interface where users can select options from a menu to perform different operations. This is a common pattern in real-world applications, calculators, and interactive programs.

1. What This Program Does

The program creates an interactive menu system that allows users to:

  • View a menu of available operations
  • Select an option by entering a number
  • Perform the selected operation (Add, Subtract, Multiply, Divide)
  • Continue until the user chooses to exit

The program runs in a loop, displaying the menu repeatedly until the user selects the exit option.

2. Header File Used

#include <iostream>

This header provides:

  • cout for displaying output
  • cin for taking input from the user

3. Understanding Menu-Driven Programs

Key Components:

  • Menu display function
  • User input for choice
  • Switch-case for option handling
  • Loop to keep program running
  • Exit condition

Benefits:

  • User-friendly interface
  • Clear organization of operations
  • Easy to extend with new options
  • Professional program structure

4. Function: displayMenu()

void displayMenu() { cout << "\n=== MENU ===" << endl; cout << "1. Add" << endl; cout << "2. Subtract" << endl; cout << "3. Multiply" << endl; cout << "4. Divide" << endl; cout << "5. Exit" << endl; cout << "Enter your choice: "; }

How it works:

  • Displays all available options
  • Numbers (1-5) represent different operations
  • Clear formatting for readability
  • Called before each user input

5. Declaring Variables

The program declares: int choice; double num1, num2, result;

  • choice stores the user's menu selection (1-5)
  • num1, num2 store the two numbers for operations
  • result stores the calculation result
  • double is used to handle decimal numbers

6. Main Loop: do-while

do { displayMenu(); cin >> choice; // ... operations ... } while(choice != 5);

How it works:

  • do-while ensures menu displays at least once
  • Loop continues while choice is not 5 (Exit)
  • Menu is displayed before each iteration
  • User can perform multiple operations

Why do-while?:

  • Guarantees menu is shown at least once
  • Better user experience than while loop
  • Natural flow for menu-driven programs

7. Input Validation

if (choice >= 1 && choice <= 4) { cout << "Enter two numbers: "; cin >> num1 >> num2; }

How it works:

  • Only asks for numbers if operation needs them
  • Options 1-4 require two numbers
  • Option 5 (Exit) doesn't need numbers
  • Prevents unnecessary input prompts

8. Switch-Case for Operations

switch(choice) { case 1: result = num1 + num2; cout << "Result: " << result << endl; break; case 2: result = num1 - num2; cout << "Result: " << result << endl; break; case 3: result = num1 * num2; cout << "Result: " << result << endl; break; case 4: if (num2 != 0) { result = num1 / num2; cout << "Result: " << result << endl; } else { cout << "Error: Division by zero!" << endl; } break; case 5: cout << "Exiting..." << endl; break; default: cout << "Invalid choice!" << endl; }

How it works:

  • Each case handles one menu option
  • Case 1-4: perform arithmetic operations
  • Case 4: includes division by zero check
  • Case 5: exit message
  • default: handles invalid input

Division by Zero Check:

  • Important safety feature
  • Prevents program crash
  • Provides user-friendly error message

9. Other Methods (Mentioned but not shown in code)

Method 2: Using Functions

void add() { /* addition logic / } void subtract() { / subtraction logic */ } // ... other functions ... switch(choice) { case 1: add(); break; case 2: subtract(); break; // ... }

  • Each operation in separate function
  • More modular and organized
  • Easier to maintain and test

Method 3: Using Classes

class Calculator { void add() { /* ... / } void subtract() { / ... */ } // ... };

  • Object-oriented approach
  • Encapsulates operations
  • Better for complex programs

10. When to Use Menu-Driven Programs

Real-World Applications:

  • Calculators and tools
  • Database management systems
  • File management programs
  • Interactive applications

Educational Purposes:

  • Learning program structure
  • Understanding user interaction
  • Practicing switch-case statements
  • Building complete programs

11. Important Considerations

Input Validation:

  • Check for valid menu choices
  • Validate numeric input
  • Handle division by zero
  • Provide clear error messages

User Experience:

  • Clear menu formatting
  • Informative messages
  • Easy exit option
  • Consistent interface

Error Handling:

  • Invalid choices
  • Invalid input types
  • Division by zero
  • Edge cases

12. return 0;

This ends the program successfully.

Summary

  • Menu-driven programs provide user-friendly interactive interfaces.
  • do-while loop ensures menu displays at least once.
  • Switch-case handles different menu options efficiently.
  • Input validation prevents errors and improves user experience.
  • Division by zero check is essential for safety.
  • Functions and classes can organize operations better.
  • Understanding menu-driven structure is essential for real-world applications.

This program is fundamental for beginners learning program structure, user interaction, switch-case statements, and preparing for building complete interactive applications in C++ programs.

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Scientific Calculator