EnumChildWindows (Win32 error 127) (c#)

[Ryan Ross]

Hello,

I am having the oddest error with the EnumChildWindows function. Below are
the imports, and the methods.

[DllImport("user32.dll", SetLastError=true)]

public static extern int EnumChildWindows(IntPtr hWndParent, EnumChildProc
callback, int lParam);

public delegate int EnumChildProc(IntPtr hwnd, long lParam);



public void M_initChildWindows()

{

if(WindowObject_Basic_GDI_Handle != IntPtr.Zero)

{

try

{

User32.EnumChildWindows(WindowObject_Basic_GDI_Handle, new
User32.EnumChildProc(M_addChildWindows), 0);

}

catch(Exception e)

{

System.Diagnostics.Debug.WriteLine("Child Window failure: " +
e.Message);

}

}


}

private int M_addChildWindows(IntPtr Window, long Data)

{


if(Window != IntPtr.Zero)

{

ChildWindowObject_Basic c_WindowObject_Basic = new
ChildWindowObject_Basic(Window);

c_WindowObject_Basic_Array.Add(c_WindowObject_Basic);

}




return 1;

}



I keep getting a 127 error, even though it appears to enumerate the windows.
I placed it within a try statement to continue working other things, but
it's coming back to bite me in the ass.



Anyone have any ideas?



Thanks,

Ryan

 

[Nicholas Paldino [.NET/C# MVP]]

Ryan,

Your declaration of the callback delegate and function is incorrect. It
should be:

[DllImport("user32.dll", SetLastError=true)]
public static extern int EnumChildWindows(IntPtr hWndParent, EnumChildProc
callback, IntPtr lParam);

public delegate int EnumChildProc(IntPtr hwnd, IntPtr lParam);

LPARAM translates to an IntPtr.

Also, as an aside, you might want to check your publicly exposed method
names. They violate the public naming convention (M_initChildWindows, for
example).

Hope this helps.