using System;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("-------------------------");

        Console.WriteLine("TC6's Calculator - v0.1");

        Console.WriteLine("-------------------------");

        Console.WriteLine("1. Addition");

        Console.WriteLine("2. Subtraction");

        Console.WriteLine("3. Multiplication");

        Console.WriteLine("-------------------------");

​

        Console.Write("Enter your choice: ");

        int choice;

        string input = "";

​

        try

        {

            input = Console.ReadLine();

            choice = Convert.ToInt32(input);

        }

        catch (FormatException)

        {

            Console.WriteLine("Error: Invalid input! You cannot input: '" + input + "' as that is not a Integer!");

            return;

        }

        Console.Write("Enter the first number: ");

        double num1;

        string input1 = "";

​

        try

        {

            input1 = Console.ReadLine();

            num1 = Convert.ToInt32(input1);

        }

        catch (FormatException)

        {

            Console.WriteLine("Error: Invalid input! You cannot input: '" + input1 + "' as that is not a Integer!");

            return;

        }

​

        double result = 0;

​

        if (choice == 1 || choice == 2 || choice == 3)

        {

            Console.Write("Enter the second number: ");

            double num2;

            string input2 = "";

​

            try

            {

                input2 = Console.ReadLine();

                num2 = Convert.ToInt32(input2);;

            }

            catch (FormatException)

            {

                Console.WriteLine("Error: Invalid input! You cannot input: '" + input2 + "' as that is not a Integer!");;

                return;

            }

​

            if (choice == 1)

            {

                result = num1 + num2;

                Console.WriteLine("Addition: " + num1 + " + " + num2 + " = " + result + ".");

            }

            else if (choice == 2)

            {

                result = num1 - num2;

                Console.WriteLine("Subtraction: " + num1 + " - " + num2 + " = " + result + ".");

            }

            else if (choice == 3)

            {

                result = num1 * num2;

                Console.WriteLine("Multiplication: " + num1 + " x " + num2 + " = " + result + ".");

            }

            Console.WriteLine("-------------------------");

        }

        else

        {

            Console.WriteLine("Error: Invalid input! Please pick a number listed below:");

            Console.WriteLine("1. Addition");

            Console.WriteLine("2. Subtraction");

            Console.WriteLine("3. Multiplication");

            Console.WriteLine("-------------------------");

        }

    }

}

​

​