Sending key presses to other applications without Windows Forms

c#
using System;
using System.Linq;
using WindowsInput.Native;
using System.Runtime.InteropServices;
using System.Collections.Generic;

public class KeyboardSimulator
{
    [DllImport("user32.dll")]
    static extern uint SendInput(uint nInputs, [MarshalAs(UnmanagedType.LPArray), In] INPUT[] pInputs, int cbSize);

    [StructLayout(LayoutKind.Sequential)]
    public struct INPUT
    {
        public uint type;
        public InputUnion U;
        public static int Size
        {
            get { return Marshal.SizeOf(typeof(INPUT)); }
        }
    }

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

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

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

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

c#
using System;
using System.Linq;
using WindowsInput.Native;
using System.Runtime.InteropServices;
using System.Collections.Generic;

public class KeyboardSimulator
{
    [DllImport("user32.dll")]
    static extern uint SendInput(uint nInputs, [MarshalAs(UnmanagedType.LPArray), In] INPUT[] pInputs, int cbSize);

    [StructLayout(LayoutKind.Sequential)]
    public struct INPUT
    {
        public uint type;
        public InputUnion U;
        public static int Size
        {
            get { return Marshal.SizeOf(typeof(INPUT)); }
        }
    }

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

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

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

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

c#
public void SimulateKeyPresses(string keys, string target)
    {
        const uint INPUT_KEYBOARD = 1;
        const uint KEYEVENTF_KEYUP = 0x0002;

        var keyList = keys.Split(' ').Select(k => Enum.Parse<VirtualKeyCode>(k.ToUpper())).ToList();
        ushort KeyCode = 0;

        if (keyList.Count == 0) return;

        List<INPUT> inputs = new List<INPUT>();

        // Press down each key
        foreach (var key in keyList)
        {
            KeyCode = (ushort)key;
            inputs.Add(new INPUT
            {
                type = INPUT_KEYBOARD,
                U = new InputUnion
                {
                    ki = new KEYBDINPUT
                    {
                        wVk = KeyCode,
                        dwFlags = 0
                    }
                }
            });
        }

        // Release each key
        foreach (var key in keyList)
        {
            KeyCode = (ushort)key;
            inputs.Add(new INPUT
            {
                type = INPUT_KEYBOARD,
                U = new InputUnion
                {
                    ki = new KEYBDINPUT
                    {
                        wVk = KeyCode,
                        dwFlags = KEYEVENTF_KEYUP
                    }
                }
            });
        }

        // Send the input events
        SendInput((uint)inputs.Count, inputs.ToArray(), INPUT.Size);
    }

c#
public void SimulateKeyPresses(string keys, string target)
    {
        const uint INPUT_KEYBOARD = 1;
        const uint KEYEVENTF_KEYUP = 0x0002;

        var keyList = keys.Split(' ').Select(k => Enum.Parse<VirtualKeyCode>(k.ToUpper())).ToList();
        ushort KeyCode = 0;

        if (keyList.Count == 0) return;

        List<INPUT> inputs = new List<INPUT>();

        // Press down each key
        foreach (var key in keyList)
        {
            KeyCode = (ushort)key;
            inputs.Add(new INPUT
            {
                type = INPUT_KEYBOARD,
                U = new InputUnion
                {
                    ki = new KEYBDINPUT
                    {
                        wVk = KeyCode,
                        dwFlags = 0
                    }
                }
            });
        }

        // Release each key
        foreach (var key in keyList)
        {
            KeyCode = (ushort)key;
            inputs.Add(new INPUT
            {
                type = INPUT_KEYBOARD,
                U = new InputUnion
                {
                    ki = new KEYBDINPUT
                    {
                        wVk = KeyCode,
                        dwFlags = KEYEVENTF_KEYUP
                    }
                }
            });
        }

        // Send the input events
        SendInput((uint)inputs.Count, inputs.ToArray(), INPUT.Size);
    }