using System;

public class Start

{

    public static void Main()

    {

        TicTacToe ticTacToe= new TicTacToe();

        ticTacToe.Start();

    }

}

​

public class TicTacToe

{

    public class TicTacToeField

    {

        public string[] values = {"1", "2", "3", "4", "5", "6", "7", "8", "9",};

        public void showBoard()

        {

            for (int i = 0; i < values.Length; i++)

            {

                if (i % 3 == 0)

                {

                    Console.WriteLine();

                }

                Console.Write(values[i]);

            }

            Console.WriteLine();

            Console.WriteLine();

        }

    }

    public string pX;

    public string pO;

    public string currentPlayer = "X";

    public void Start()

    {

        TicTacToeField playfield = new TicTacToeField();

        Console.WriteLine("Name player X:");

        pX = Console.ReadLine();

        Console.WriteLine("Name player O:");

        pO = Console.ReadLine();

        playfield.showBoard();

        Rounds();

    }

    public void Rounds()

    {

        if (currentPlayer == "X")

        {

            Console.WriteLine(pX + " may choose a location for X:");

            int fieldNumber = GetFieldNumber();

        }

        else

        {

            Console.WriteLine(pO + "may choose a location for O:");

        }

    }

    int GetFieldNumber()

    {

        int fieldNumber;

        string input = Console.ReadLine();

        bool isNumber = int.TryParse(input, out fieldNumber);

        if (isNumber)

        {

            return fieldNumber;

        }

        else

        {

            Console.WriteLine(pX + "Give a valid answer:");

            return GetFieldNumber();

        }

    }   

}