c# midterm1 exercises from deitel

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace midterm1console
{
    class Program
    {
        static void Main(string[] args)
        {
            int choose;
            string menu = "1-GEOMETRIC CALCULATION\n" +
                        "2-MULTIPLE TEST\n" +
                        "3-RANDOM NUMBER TEST\n" +
                        "4-PALINDROME TEST\n" +
                        "5-PHONE NUMBER ENCRYPT\n" +
                        "6-FUNCTION OVERLOADING\n";

            Console.WriteLine(menu);
            Console.WriteLine("choose one of them: ");
            choose = int.Parse(Console.ReadLine());
            switch (choose)
            {
                case 1:
                    double pi = Math.PI;
                    double radius, area, circum, diameter;
                    int num1, num2;

                    ////GEOMETRIC CALCULATER TEST
                    Console.WriteLine("enter the radius: ");
                    radius = double.Parse(Console.ReadLine());

                    area = pi * radius * radius;
                    Console.WriteLine("area: {0}", area);

                    diameter = 2 * radius;
                    Console.WriteLine("diameter: {0}", diameter);

                    circum = 2 * pi * radius;
                    Console.WriteLine("circumference: {0}", circum);
                    break;

                case 2:
                    ///MULTIPLE TEST
                    Console.WriteLine("\n\n#############################\n\n");

                    Console.WriteLine("enter num1: ");
                    num1 = int.Parse(Console.ReadLine());

                    Console.WriteLine("enter num2: ");
                    num2 = int.Parse(Console.ReadLine());

                    if ((num1 % num2) == 0)
                        Console.WriteLine("the first number is a multiple of the second.");
                    else
                        Console.WriteLine("the first number is not a multiple of the second.");

                    break;

                case 3:
                    //RANDOM NUMBER TEST
                    Random random = new Random(System.DateTime.Now.Millisecond);
                    int num = random.Next(1, 1000);
                    Console.WriteLine("\n\nrandom: {0}", num);
                    break;

                case 4:
                    ///PALINDROME TEST
                    Console.WriteLine("\n\nenter five-digit-number: ");
                    int palindrome;
                    palindrome = int.Parse(Console.ReadLine());
                    string test = palindrome.ToString();
                    try
                    {
                        if (test[0] == test[4] && test[1] == test[3])
                            Console.WriteLine("\n\nit is a palindrome");
                        else
                            Console.WriteLine("\n\nit is not a palindrome");
                    }
                    catch (Exception e)
                    {
                        if (test.Length != 5)
                            Console.WriteLine("You must enter five digit!");
                        else
                            Console.WriteLine("something was wrong!");
                    }
                    break;

                case 5:
                    //ENCRYPT PHONE NUMBER
                    int phone_num;
                    string temp, crypt = "";
                    Console.WriteLine("\n\nenter phone num: ");
                    phone_num = int.Parse(Console.ReadLine());
                    temp = phone_num.ToString();
                    for (int i = 0; i < temp.Length; i++)
                    {
                        string c = temp[i].ToString();
                        int x = int.Parse(c);
                        crypt = crypt + ((x + 7) % 10).ToString();
                    }
                    Console.WriteLine("crypted num: {0}", crypt);

                    //DECRYPT PHONE NUMMER
                    int phone;
                    string decrypt = "";
                    for (int i = 0; i < crypt.Length; i++)
                    {
                        string c = crypt[i].ToString();
                        int x = int.Parse(c);
                        if (10 == (10 + x) - 7)
                            decrypt = decrypt + (0).ToString();
                        else if (11 == (10 + x) - 7)
                            decrypt = decrypt + (1).ToString();
                        else if (12 == (10 + x) - 7)
                            decrypt = decrypt + (2).ToString();
                        else
                            decrypt = decrypt + ((10 + x) - 7).ToString();
                    }
                    phone = int.Parse(decrypt);
                    Console.WriteLine("decrypted num: {0}", phone);
                    break;


                //FUNCTION OVERLOADING TEST
                case 6:
                    int k = 2, m = 5;
                    double n = 3.5, h = 5.25;
                    Console.WriteLine("integer addition result: {0}", add(k, m));
                    Console.WriteLine("double addition reslult: {0}", add(n, h));
                    break;

                default:
                    Console.WriteLine("enter only 1-5 !!!");
                    break;
            }

            Console.ReadKey();
        }

        static int add(int x, int y)
        {
            return x + y;
        }

        static double add(double x, double y)
        {
            return x + y;
        }

    }
}