C#

string address = "test@g.com";
string[] host = (address.Split('@'));
string hostname = host[1];
     
IPHostEntry IPhst = Dns.Resolve(hostname);
IPEndPoint endPt = new IPEndPoint(IPhst.AddressList[0], 25);
Socket s= new Socket(endPt.AddressFamily, 
        SocketType.Stream,ProtocolType.Tcp);
s.Connect(endPt);

<files>
   <file id="1" name="(some guid)"/>
   <file id="2" name="(some guid)"/>
</files>

<file id="1">
   <prop1>Value 1</prop1>
   <prop1>Value 1</prop1>
   <prop1>Value 1</prop1>
</file>

private void button1_Click(object sender, EventArgs e)
        {
            string file_name = "C:/test1.txt";

            System.IO.StreamReader objReader;
            objReader = new System.IO.StreamReader(file_name);

            textBox1.Text = objReader.ReadToEnd();

            objReader.Close();
        }

An unhandled exception of type 'System.Data.SqlClient.SqlException' occurred in System.Windows.Forms.dll

Additional information: SqlException

static string connectionString = "Data Source=192.168.2.132; Initial Catalog=MDetectorDatabase; Integrated Security=true";

private void SubmitButton_Click(object sender, EventArgs e)
        {
            string login = this.loginTextBox.Text;
            string passw = this.passwTextBox.Text;
            string user = "";

            SqlConnection loginConnection = new SqlConnection(connectionString);
            string loginquery = "SELECT * FROM Doctors Where UserName='" + login + "';";
            SqlCommand loginCommand = new SqlCommand(loginquery, loginConnection);

            loginConnection.Open();

            SqlDataReader loginReader = loginCommand.ExecuteReader();
            ...
        }