Untitled

using System;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Collections.Generic;
using System.ComponentModel;
using System.Net.Sockets;
using System.Threading;
using System.IO;

}
namespace socket_programming
{
    public partial class Form1 : Form
    {
        bool terminating = false;
        bool connected = false;
        
        Socket clientSocket;
        public Form1()
        {
            Control.CheckForIllegalCrossThreadCalls = false;
            InitializeComponent();
            this.FormClosing += new FormClosingEventHandler(Form1_FormClosing);
        }
        private void button_connect_click(object sender, EventArgs e)
        {
            clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            string IP = textBox1_ip.Text;
            int portNum;
            if (Int32.TryParse(textBox2_port.Text, out portNum))
            {
                try
                {
                    clientSocket.Connect(IP, portNum);
                    button2_createAccount.Enable = true; //initially false

                    textBox3_name.Enabled = true; //initially false
                    textBox4_surname.Enabled = true;
                    textBox5_username.Enabled = true;
                    textBox6_password.Enabled = true;

                    button_connect.Enabled = false;
                    connected = true;
                    clientlogs.AppendText("You are connected!\n");

                    Thread receivethread = new Thread(Receive);
                    recievethread.Start();

                }
                catch
                {
                    //if the server is not listed
                    clientlogs.AppendText("Could not connect to the server!\n");
                }
                
            }
            else
            {
                clientlogs.AppendText("Check your port number!\n");
            }
        }
        private void Receive()
        {
            while (connected)
            {

                try
                {
                    Byte[] username = new byte[64]; //message travels as a byte array form such as usernames serder'dan yazdir
                    clientSocket.Receive(username);
                    string received_username = Encoding.Default.GetString(username);
                    received_username = received_username.Substring(0, received_username.IndexOf("\0"));
                    //suggestion: you can use .Trim('\0')

                }
                catch
                {
                    if (!terminating)
                    {
                        clientlogs.AppendText("The server has disconnected.\n");
                        button_connect.Enabled = true;

                        textBox3_name.Enabled = false;
                        textBox4_surname.Enabled = false;
                        textBox5_username.Enabled = false;
                        textBox6_password.Enabled = false;

                        button2_createAccount.Enabled = false;
                    }
                    clientSocket.Close();
                    connected = false;
                }
                var lines = File.ReadLines(@"/Users/bengisuozdemir/Documents/database.txt");

                using (StreamWriter file = new StreamWriter("/Users/bengisuozdemir/Documents/database.txt", append: true))
                {
                    file.WriteLine(username + "-");
                }
            }
            
        }
        private void button2_createAccountClick(object sender, EventArgs e)
        {
            string Name = textBox3_name.Text();
            string Surname = textBox4_surname.Text();
            string Username = textBox5_username.Text();
            string Password = textBox6_password.Text();

            

            if (Username != "")//also can check the lenght if it's equal to 64 bytes
            {
                Byte[] bufferU = Encoding.Default.GetBytes(Username);
                clientSocket.Send(bufferU);

                if(true)//if the .txt file does not contain entered username
                    {
                    clientlogs.AppendText("You have created a new account!\n");
                }
                    else
                {
                    clientlogs.AppendText("There is already an account with this username!\n");
                }

            }
            else
            {
                clientlogs.AppendText("Please enter a username!\n");
            }
            if (Name != "")//also can check the lenght if it's equal to 64 bytes
            {
                Byte[] bufferN = Encoding.Default.GetBytes(Name);
                clientSocket.Send(bufferN);
            }
            else
            {
                clientlogs.AppendText("Please enter a name!\n");
            }
            if (Surname == "")//also can check the lenght if it's equal to 64 bytes
            {
                Byte[] bufferS = Encoding.Default.GetBytes(Surname);
                clientSocket.Send(bufferS);
            }
            else
            {
                clientlogs.AppendText("Please enter a surname!\n");
            }
            if (Password != "")//also can check the lenght if it's equal to 64 bytes
            {
                Byte[] bufferP = Encoding.Default.GetBytes(Password);
                clientSocket.Send(bufferP);
            }
            else
            {
                clientlogs.AppendText("Please enter a password!\n");
            }

        }
        private void Form1_FormClosing(object sender, System.ComponentModel.CancelEventArgs e)
        {
            connected = false;
            terminating = true;
            Environment.Exit(0);
        }
    }
}

////



using System;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Collections.Generic;
using System.ComponentModel;
using System.Net.Sockets;
using System.Threading;
using System.Net;
using System.Threading;

namespace server
{
    public partial class Form1 : Form1
    {
        Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        List<Socket> clientSockets = new List<Socket>();

        bool terminating = false;
        bool listening = false;

        public Form1()
        {
            Control.CheckForIllegalCrossThreadCalls = false;
            InitializeComponent();
            this.FormClosing += new FormClosingEventHandler(Form1_FormClosing);
        }
        private void button_listen_Click(object sender, EventArgs e)
        {
            int serverPort;
            if (Int32.TryParse(textBox_port.Text, out serverPort))
            {
                IPEndPoint endPoint = new IPEndPoint(IPAddress.Any, serverPort);
                serverSocket.Bind(endPoint);
                serverSocket.Listen(3); //get username status

                listening = true;
                button_listen.Enabled = false;
                textBox_message.Enabled = true;
                button_createAcccount = true;

                Thread acceptThread = new Thread(Accept);
                acceptThread.Start();

                logs.AppendText("");

            }
            else
            {
                logs.AppendText("");

            }
        }
        private void Accept()
        {
            while (listening)
            {
                try
                {
                    Socket newClient = serverSocket.Accept();
                    clientSockets.Add(newClient);
                    logs.AppendText("A client has connected!\n");

                    Thread recieveThread = new Thread(() => Receive(newClient));
                }
                catch
                {
                    if (terminating)
                    {
                        listening = false;
                    }
                    else
                    {
                        logs.AppendText("The socket stopped working.\n");
                    }
                }
            }
        }
        private void Receive(Socket thisClient)
        {
            bool connected = true;
            while(connected && !terminating)
            {
                try
                {
                    Byte[] buffer = new byte[64];
                    thisClient.Receive(buffer);

                    string incomingUsername = Encoding.Default.GetString(buffer);
                    incomingUsername = incomingUsername.Substring(0, incomingUsername.IndexOf("\0"));
                    logs.AppendText(incomingUsername + " has created an account.");
                }
                catch
                {
                    if (!terminating)
                    {
                        logs.AppendText("A client has disconnected.\n");
                    }
                    thisClient.Close();
                    clientSockets.Remove(thisClient);
                    connected = false;
                }
            }
        }
        
    }
}