[DllImport("kernel32.dll",

EntryPoint = "GetComputerName",

ExactSpelling = false,

SetLastError = true)]

        static extern bool GetComputerName(

        [MarshalAs(UnmanagedType.LPArray)] byte[] lpBuffer,

        [MarshalAs(UnmanagedType.LPArray)] Int32[] nSize);  

        public Form1()

        {

            InitializeComponent();

            byte[] str = new byte[20];

            Int32[] len = new Int32[1];

            len[0] = 20;

            GetComputerName(str, len);

            MessageBox.Show(System.Text.Encoding.ASCII.GetString(str));  

}