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c#winapimessagebox

Click on 'OK' button of message box using WinAPI in C#

I am trying to click on 'OK' button on a message box of C# Windows Forms using WinAPI . Below is the code that I am working on.

private const int WM_CLOSE = 16;
private const int BN_CLICKED = 245;

[DllImport("user32.dll", CharSet=CharSet.Auto)]
public static extern int SendMessage(int hWnd, int msg, int wParam, IntPtr lParam);

[DllImport("user32.dll", SetLastError = true)]
public static extern IntPtr FindWindowEx(IntPtr parentHandle, IntPtr childAfter, string className,  string  windowTitle);

// this works
hwnd = FindWindow(null, "Message");
if(hwnd!=0)
      SendMessage(hwnd, WM_CLOSE, 0, IntPtr.Zero);

// this doesn't work.
hwndChild = FindWindowEx((IntPtr)hwnd, IntPtr.Zero, "Button", "ok");
SendMessage((int)hwndChild, BN_CLICKED, 0, IntPtr.Zero);

Though I get a value in hwndChild, it is not recognising BN_CLICKED. I am not sure what am I missing. any help?

I am trying to close the message box button of another application and this is what I am doing. But, I m still missing something.

IntPtr hwndChild = IntPtr.Zero;
hwndChild = FindWindowEx((IntPtr)hwnd, IntPtr.Zero,' '"Button", "OK");
SendMessage((int)hwndChild, WM_COMMAND, (BN_CLICKED '<<16) | IDOK, hwndChild);
Solution

  • Finallu, this works for me. First click probably activates the window and second click clicks the button.

    SendMessage(btnHandle, WM_LBUTTONDOWN, 0, 0);
SendMessage(btnHandle, WM_LBUTTONUP, 0, 0);
SendMessage(btnHandle, WM_LBUTTONDOWN, 0, 0);
SendMessage(btnHandle, WM_LBUTTONUP, 0, 0);