C# Signature:

[DllImport("coredll")]
public static extern int SendMessage(IntPtr hWnd, uint Msg, int wParam, int lParam);

VB Signature:

Declare Function SendMessage Lib "coredll.dll" (ByVal hWnd As IntPtr, ByVal Msg As Integer, ByVal wParam As Integer, ByVal lParam As Integer) As IntPtr

Notes:

If you are searching for a way to send keys to an application, you can use System.Windows.Forms.SendKeys.Send(keys) after bringing the window to the top via the SetForegroundWindow API.

Tips & Tricks:

Sample Code:

    public partial class Form1 : Form
    {
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        //Down
        User32.SendMessage(listView1.Handle, User32.WM.WM_KEYDOWN, (int)User32.VK.VK_DOWN, 0);
        User32.SendMessage(listView1.Handle, User32.WM.WM_KEYUP, (int)User32.VK.VK_DOWN, 0);
    }

    private void button2_Click(object sender, EventArgs e)
    {
        //Up
        User32.SendMessage(listView1.Handle, User32.WM.WM_KEYDOWN, (int)User32.VK.VK_UP, 0);
        User32.SendMessage(listView1.Handle, User32.WM.WM_KEYUP, (int)User32.VK.VK_UP, 0);
    }

    //Left ... Right...
    }

    class User32
    {
    [System.Runtime.InteropServices.DllImport("coredll.dll")]
    public static extern int SendMessage(IntPtr hWnd, WM Msg, int wParam, int lParam);

    public enum VK : int
    {
        VK_DOWN = 0x28,
        VK_UP = 0x26,
        VK_LEFT = 0x25,
        VK_RIGHT = 0x27
    }

    public enum WM
    {
        WM_KEYUP = 0x0101,
        WM_KEYDOWN = 0x0100
    }
    }

Alternative Managed API:

Do you know one? Please contribute it!

Please edit this page!

Do you have...

• helpful tips or sample code to share for using this API in managed code?
• corrections to the existing content?
• variations of the signature you want to share?
• additional languages you want to include?

Select "Edit This Page" on the right hand toolbar and edit it! Or add new pages containing supporting types needed for this API (structures, delegates, and more).