Menu-Driven Temperature Conversion (Celsius ⇄ Fahrenheit)

Formulate an interactive menu-driven console application with options: 1. Convert Celsius to Fahrenheit, 2. Convert Fahrenheit to Celsius, 3. Exit. The loop repeats until the user chooses option 3, with validation for invalid menu entries.

Step 1: Start.
Step 2: Display Menu:
         1. Celsius to Fahrenheit
         2. Fahrenheit to Celsius
         3. Exit
Step 3: Read Choice.
Step 4: If Choice == 1:
         Read Celsius C.
         F = (C * 9 / 5) + 32.
         Print F.
         Go to Step 2.
Step 5: Else if Choice == 2:
         Read Fahrenheit F.
         C = (F - 32) * 5 / 9.
         Print C.
         Go to Step 2.
Step 6: Else if Choice == 3:
         Print 'Exiting program. Goodbye!'
         Go to Step 8.
Step 7: Else:
         Print 'Invalid Choice! Please enter 1, 2, or 3.'
         Go to Step 2.
Step 8: Stop.

         +-----------------+
         |     [ START ]   |
         +-----------------+
                  |
                  v
         +-----------------+
+------> |  Display Menu   |
|        |   Read Choice   |
|        +-----------------+
|                 |
|                 v
|              /     \
|            /Choice==1?\ ---YES--> [Read C -> F=C*9/5+32 -> Print F] --+
|            \         /                                               |
|                 | NO                                                 |
|                 v                                                    |
|              /     \                                                 |
|            /Choice==2?\ ---YES--> [Read F -> C=(F-32)*5/9 -> Print C]-+
|            \         /                                               |
|                 | NO                                                 |
|                 v                                                    |
|              /     \                                                 |
|            /Choice==3?\ ---YES--> [Print Goodbye] --> [ STOP ]       |
|            \         /                                               |
|                 | NO                                                 |
|                 v                                                    |
|        +-----------------+                                           |
+------- |  Print Invalid  | <-----------------------------------------+
         +-----------------+

Edit the code directly with the Edit Code button, provide custom inputs, and press Run Code to compile and execute in the live terminal console below!

#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    int choice;
    cout << fixed << setprecision(2);

    do {
        cout << "\n========================================\n";
        cout << "   TEMPERATURE CONVERTER SYSTEM MENU    \n";
        cout << "========================================\n";
        cout << "  1. Celsius to Fahrenheit (C -> F)\n";
        cout << "  2. Fahrenheit to Celsius (F -> C)\n";
        cout << "  3. Exit Application\n";
        cout << "----------------------------------------\n";
        cout << "Enter your choice (1 - 3): ";

        if (!(cin >> choice)) {
            cout << "Invalid input! Exiting program...\n";
            break;
        }

        switch (choice) {
            case 1: {
                double c;
                cout << "Enter temperature in Celsius (°C): ";
                cin >> c;
                double f = (c * 9.0 / 5.0) + 32.0;
                cout << ">>> Result: " << c << " °C = " << f << " °F\n";
                break;
            }
            case 2: {
                double f;
                cout << "Enter temperature in Fahrenheit (°F): ";
                cin >> f;
                double c = (f - 32.0) * (5.0 / 9.0);
                cout << ">>> Result: " << f << " °F = " << c << " °C\n";
                break;
            }
            case 3:
                cout << "\nThank you for using Temperature Converter. Goodbye!\n";
                break;
            default:
                cout << "\n[!] Error: Invalid selection! Please enter 1, 2, or 3.\n";
                break;
        }

    } while (choice != 3);

    return 0;
}

Input:
1
100
3

Output:
>>> Result: 100.00 °C = 212.00 °F
Thank you for using Temperature Converter. Goodbye!