SendInput C#

using System;
using System.Diagnostics;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
  class DirectInput
  {
    public enum VK : ushort
    {
      SHIFT = 0x10,
      CONTROL = 0x11,
      MENU = 0x12,
      ESCAPE = 0x1B,
      BACK = 0x08,
      TAB = 0x09,
      RETURN = 0x0D,
      PRIOR = 0x21,
      NEXT = 0x22,
      END = 0x23,
      HOME = 0x24,
      LEFT = 0x25,
      UP = 0x26,
      RIGHT = 0x27,
      DOWN = 0x28,
      SELECT = 0x29,
      PRINT = 0x2A,
      EXECUTE = 0x2B,
      SNAPSHOT = 0x2C,
      INSERT = 0x2D,
      DELETE = 0x2E,
      HELP = 0x2F,
      NUMPAD0 = 0x60,
      NUMPAD1 = 0x61,
      NUMPAD2 = 0x62,
      NUMPAD3 = 0x63,
      NUMPAD4 = 0x64,
      NUMPAD5 = 0x65,
      NUMPAD6 = 0x66,
      NUMPAD7 = 0x67,
      NUMPAD8 = 0x68,
      NUMPAD9 = 0x69,
      MULTIPLY = 0x6A,
      ADD = 0x6B,
      SEPARATOR = 0x6C,
      SUBTRACT = 0x6D,
      DECIMAL = 0x6E,
      DIVIDE = 0x6F,
      F1 = 0x70,
      F2 = 0x71,
      F3 = 0x72,
      F4 = 0x73,
      F5 = 0x74,
      F6 = 0x75,
      F7 = 0x76,
      F8 = 0x77,
      F9 = 0x78,
      F10 = 0x79,
      F11 = 0x7A,
      F12 = 0x7B,
      OEM_1 = 0xBA,  // ',:' for US
      OEM_PLUS = 0xBB,  // '+' any country
      OEM_COMMA = 0xBC,  // ',' any country
      OEM_MINUS = 0xBD,  // '-' any country
      OEM_PERIOD = 0xBE,  // '.' any country
      OEM_2 = 0xBF,  // '/?' for US
      OEM_3 = 0xC0,  // '`~' for US
      MEDIA_NEXT_TRACK = 0xB0,
      MEDIA_PREV_TRACK = 0xB1,
      MEDIA_STOP = 0xB2,
      MEDIA_PLAY_PAUSE = 0xB3,
      LWIN = 0x5B,
      RWIN = 0x5C
    }

    [StructLayout(LayoutKind.Sequential)]
    struct MOUSEINPUT
    {
      public int dx;
      public int dy;
      public int mouseData;
      public int dwFlags;
      public int time;
      public IntPtr dwExtraInfo;
    }

    [StructLayout(LayoutKind.Sequential)]
    struct KEYBDINPUT
    {
      public short wVk;
      public short wScan;
      public int dwFlags;
      public int time;
      public IntPtr dwExtraInfo;
    }

    [StructLayout(LayoutKind.Sequential)]
    struct HARDWAREINPUT
    {
      public int uMsg;
      public short wParamL;
      public short wParamH;
    }

    [StructLayout(LayoutKind.Explicit)]
    struct INPUT
    {
      [FieldOffset(0)]
      public int type;
      [FieldOffset(4)]
      public MOUSEINPUT mi;
      [FieldOffset(4)]
      public KEYBDINPUT ki;
      [FieldOffset(4)]
      public HARDWAREINPUT hi;
    }

    [DllImport("user32.dll")]
    static extern uint SendInput(uint nInputs, INPUT[] pInputs, int cbSize);

    public static void Send(String message)
    {
      INPUT[] input = new INPUT[message.Length];
      for (int i = 0; i <= message.Length - 1; i++)
      {
        input[i].type = 1;
        input[i].ki.wVk = (short)message[i];
        input[i].ki.dwFlags = 0x01;        
      }
      uint sent = SendInput((uint)input.Length, input, Marshal.SizeOf(input[0]));
    }
  }

DirectInput.Send(textBox1.Text);

private void SwitchToProcess(string m_processName)
    {
      int ret;
      IntPtr hwndMain;
      Process[] myProcesses = Process.GetProcessesByName(
        m_processName);
      foreach (Process p in myProcesses)
      {
        if (p.Id != Process.GetCurrentProcess().Id)
        {
          hwndMain = p.MainWindowHandle;
          if (IsIconic(hwndMain) != 0)
          { // Fenster minimiert?
            ret = OpenIcon(hwndMain);
            if (ret == 0)
            {
              throw new Exception(
          "Error restoring Window from icon");
            }
          }
          ret = SetForegroundWindow(hwndMain);
          if (ret == 0)
          {
            throw new Exception(
         "Error bringing Window to front");
          }
          return;
        }
      }
    }

 input[i].type = 1;
 input[i].ki.wVk = (short)message[i];
 input[i].ki.dwFlags = 0x01;

input[i].type = 1;
input[i].ki.dwFlags = 0x0004;
input[i].ki.wScan = *(short)message[i];

    public static void Send(string message)
    {
      INPUT[] input = new INPUT[message.Length];
      uint sent = 0;
      char m_prevChar = (char)0;
      for (int i = 0; i <= message.Length - 1; i++)
      {
        if (message[i] == m_prevChar)
        {
          string m_substring = message.Substring(i, message.Length - i);
          sent = SendInput((uint)input.Length, input, Marshal.SizeOf(input[0]));
          SendKeyup(input);
          Send(m_substring);
          return;
        }
        input[i].type = 1;
        input[i].ki.dwFlags = 0x04;//0x0004;
        input[i].ki.wScan = (short)message[i];
        m_prevChar = message[i];
      }
      sent = SendInput((uint)input.Length, input, Marshal.SizeOf(input[0]));
      SendKeyup(input);
    }

    public static void SendKeyup(INPUT[] input)
    {
      uint sent = 0;
      for (int i = 0; i <= input.Length-1; i++)
      {
        input[i].ki.dwFlags = 0x02;
      }
      sent = SendInput((uint)input.Length, input, Marshal.SizeOf(input[0]));
    }

 sent = SendInput((uint)input.Length, input, Marshal.SizeOf(input[0]));