phonebook

using System;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Welcome\nPlease insert number of entries");
            int entries = int.Parse(Console.ReadLine());

            if (entries != 0)
            {
                string[] names = new string[entries];
                string[] phones = new string[entries];

                int choice = -1;

                Console.WriteLine("Please select a choice from the following:\n1)Enter a new entry\n2)Delete an entry\n3)Search for an entry\n4)Show existing entries\nOr\n0)Exit");
                choice = int.Parse(Console.ReadLine());

                while (choice != 0)
                {
                    //eisageis entries
                    if (choice == 1)
                    {
                        Console.WriteLine("Entry number?");
                        int i = int.Parse(Console.ReadLine());

                        if (i < entries && i >= 0)
                        {
                            Console.WriteLine("Name?");
                            names[i] = Console.ReadLine();
                            Console.WriteLine("Phone?");
                            phones[i] = Console.ReadLine();
                        }

                        else
                        {
                            Console.WriteLine("Please insert a valid entry");
                        }
                    }

                    //diagrafeis entries
                    else if (choice == 2)
                    {
                        Console.WriteLine("Entry number?");
                        int i = int.Parse(Console.ReadLine());

                        if (i < entries && i >= 0)
                        {
                            names[i] = null;
                            phones[i] = null;
                        }

                        else
                        {
                            Console.WriteLine("Please insert a valid entry");
                        }
                    }

                    //psaxneis na breis an ena onoma pou dinei o xrhsths yparxei
                    else if (choice == 3)
                    {
                        Console.WriteLine("Name?");
                        string name = Console.ReadLine();
                        int results = 0;

                        for (int i = 0; i < entries; i++)
                        {
                            if (names[i] == name)
                            {
                                Console.WriteLine("{0}\t{1}", names[i], phones[i]);
                                results++;
                            }
                        }

                        Console.WriteLine("{0} results found", results);
                    }

                    //deixnei entries
                    else if (choice == 4)
                    {
                        Console.WriteLine("#\tName\tPnone");
                        Console.WriteLine("----------------------");

                        for (int i = 0; i < entries; i++)
                        {
                            Console.WriteLine("{0}\t{1}\t{2}", i, names[i], phones[i]);
                        }
                    }

                    else if (choice == 0)
                    {
                        Console.WriteLine("Bye");
                    }


                    else
                    {
                        Console.WriteLine("Wrong Input");
                    }
                }
            }
            Console.WriteLine("Bye");
        }
    }
}