public class Printer
    {
        // Structure and API declarions:
        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
        public class DOCINFOA
        {
            [MarshalAs(UnmanagedType.LPStr)]
            public string pDocName;
            [MarshalAs(UnmanagedType.LPStr)]
            public string pOutputFile;
            [MarshalAs(UnmanagedType.LPStr)]
            public string pDataType;
        }
        [DllImport("winspool.Drv", EntryPoint = "OpenPrinterA", SetLastError = true, CharSet = CharSet.Ansi, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool OpenPrinter([MarshalAs(UnmanagedType.LPStr)] string szPrinter, out IntPtr hPrinter, long pd);

        [DllImport("winspool.Drv", EntryPoint = "ClosePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool ClosePrinter(IntPtr hPrinter);

        [DllImport("winspool.Drv", EntryPoint = "StartDocPrinterA", SetLastError = true, CharSet = CharSet.Ansi, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool StartDocPrinter(IntPtr hPrinter, Int32 level, [In, MarshalAs(UnmanagedType.LPStruct)] DOCINFOA di);

        [DllImport("winspool.Drv", EntryPoint = "EndDocPrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool EndDocPrinter(IntPtr hPrinter);

        [DllImport("winspool.Drv", EntryPoint = "StartPagePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool StartPagePrinter(IntPtr hPrinter);

        [DllImport("winspool.Drv", EntryPoint = "EndPagePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool EndPagePrinter(IntPtr hPrinter);

        [DllImport("winspool.Drv", EntryPoint = "WritePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool WritePrinter(IntPtr hPrinter, IntPtr pBytes, Int32 dwCount, out Int32 dwWritten);

        
        /// <summary>
        /// Bytes da stampare
        /// </summary>
        /// <param name="szPrinterName">Nome stampante</param>
        /// <param name="pBytes">Bytes da stampare</param>
        /// <param name="dwCount">Numero di bytes da stampare</param>
        /// <returns>True è risuscito a stampare false altrimenti</returns>
        public static bool SendBytesToPrinter(string szPrinterName, IntPtr pBytes, Int32 dwCount)
        {
            // When the function is given a printer name and an unmanaged array
            // of bytes, the function sends those bytes to the print queue.
            // Returns true on success, false on failure.
            Int32 dwError = 0, dwWritten = 0;
            IntPtr hPrinter = new IntPtr(0);
            DOCINFOA di = new DOCINFOA();
            bool bSuccess = false; // Assume failure unless you specifically succeed.

            di.pDocName = "My C#.NET RAW Document";
            di.pDataType = "RAW";

            // Apertura connessione stampante
            if (OpenPrinter(szPrinterName, out hPrinter, 0))
            {
                // Crea Documento
                if (StartDocPrinter(hPrinter, 1, di))
                {
                    // Crea Pagina
                    if (StartPagePrinter(hPrinter))
                    {
                        // Scrivo i Bytes da stampare
                        bSuccess = WritePrinter(hPrinter, pBytes, dwCount, out dwWritten);
                        EndPagePrinter(hPrinter);
                    }
                    EndDocPrinter(hPrinter);
                }
                ClosePrinter(hPrinter);
            }
            // If you did not succeed, GetLastError may give more information
            // about why not.
            if (bSuccess == false)
            {
                dwError = Marshal.GetLastWin32Error();
            }
            return bSuccess;
        }


        /// <summary>
        /// Stampa di un bar code
        /// </summary>
        /// <param name="szPrinterName">Nome della Stampante bar Code</param>
        /// <param name="szString">stringa da stampare</param>
        /// <returns></returns>
        public static bool SendStringToPrinter(string szPrinterName, string szString)
        {
            IntPtr pBytes;
            Int32 dwCount;
            // How many characters are in the string?
            dwCount = szString.Length;
            // Assume that the printer is expecting ANSI text, and then convert
            // the string to ANSI text.
            pBytes = Marshal.StringToCoTaskMemAnsi(szString);
            // Send the converted ANSI string to the printer.
            SendBytesToPrinter(szPrinterName, pBytes, dwCount);
            Marshal.FreeCoTaskMem(pBytes);
            return true;
        }

    }