Function calculator, params and return value of Main Learn programming C#

Lesson:

Functions

Exercise:

Function calculator, params and return value of Main

Objetive:

Create a C# program to calculate a sum, subtraction, product or division, analyzing the command line parameters:

calc 5 + 379

(Parameters must be a number, a sign, and another number; allowed signs are + - * x / )

This version must return the following error codes:
1 if the number of parameters is not 3
2 if the second parameter is not an accepted sign
3 if the first or third parameter is not a valid number
0 otherwise

Code:

using System;
public class exercise126
{
    public static int Main(string[] args)
    {
        if (args.Length != 3)
        {
            Console.WriteLine("Error!");
            Console.WriteLine("Usage: number1 operand number2");
            Console.WriteLine("Where operand can be + - / * x ·");
            return 1;
        }

try
        {
            int number1 = Convert.ToInt32(args[0]);
            int number2 = Convert.ToInt32(args[2]);

switch (args[1])
            {
                case "+":
                    {
                        Console.WriteLine(number1 + number2);
                        break;
                    }

case "-":
                    {
                        Console.WriteLine(number1 - number2);
                        break;
                    }

case "/":
                    {
                        Console.WriteLine(number1 / number2);
                        break;
                    }

case "*":
                case "x":
                case "·":
                    {
                        Console.WriteLine(number1 * number2);
                        break;
                    }

default:
                    {
                        Console.WriteLine("Error!");
                        Console.WriteLine("Operand must be + - / * x or ·");
                        return 2;
                        break;
                    }
            }
        }

catch (Exception)
        {
            Console.WriteLine("Error!");
            Console.WriteLine("Not a valid number");
            return 3;
        }

return 0;
    }
}

using System;
public class exercise126
{
    public static int Main(string[] args)
    {
        if (args.Length != 3)
        {
            Console.WriteLine("Error!");
            Console.WriteLine("Usage: number1 operand number2");
            Console.WriteLine("Where operand can be + - / * x ·");
            return 1;
        }

        try
        {
            int number1 = Convert.ToInt32(args[0]);
            int number2 = Convert.ToInt32(args[2]);

            switch (args[1])
            {
                case "+":
                    {
                        Console.WriteLine(number1 + number2);
                        break;
                    }

                case "-":
                    {
                        Console.WriteLine(number1 - number2);
                        break;
                    }

                case "/":
                    {
                        Console.WriteLine(number1 / number2);
                        break;
                    }

                case "*":
                case "x":
                case "·":
                    {
                        Console.WriteLine(number1 * number2);
                        break;
                    }

                default:
                    {
                        Console.WriteLine("Error!");
                        Console.WriteLine("Operand must be + - / * x or ·");
                        return 2;
                        break;
                    }
            }
        }

        catch (Exception)
        {
            Console.WriteLine("Error!");
            Console.WriteLine("Not a valid number");
            return 3;
        }

        return 0;
    }
}