How to get a function pointer ?

[Ky Nam]

Hi I wrote this code with /clr , EnumChildWindows is C++ Interop BOOL CALLBACK EnumWindowsCallback(HWND hWnd, LPARAM lParam){} EnumChildWindows(hwnd, EnumWindowsCallback, 0); Error error C3867: 'EnumWindowsCallback': function call missing argument list; use '&EnumWindowsCallback' to create a pointer to member How to call EnumChildWindows function not using p/invoke ? Thanks :)

[dkaatz]

EnumChildWindows(hWnd, (WNDENUMPROC)&enumChildWndCallback, 0); D.

[Ky Nam]

Thank for your reply , but BOOL CALLBACK EnumWindowsCallback(HWND hWnd, LPARAM lParam){} EnumChildWindows(Handle, (WNDENUMPROC)&EnumWindowsCallback, 0); error C2276: '&' : illegal operation on bound member function expression

[Luc Pattyn]

Hi, I don't know the details in C++ but here is how I do it in C#; it takes a delegate, and code along these lines where list happened to be an ArrayList:

public delegate bool LP_EnumWindowsProc(IntPtr hWnd, int lParam);

// this call fills list with all visible windows
EnumChildWindows(hWnd, new LP_EnumWindowsProc(CollectVisibleWindows), 0);

private static bool CollectVisibleWindows(IntPtr hWnd, int lParam) {
if(IsWindowVisible(hWnd)) list.Add(hWnd);
return true; // please continue enumeration !
}

:)

Luc Pattyn [Forum Guidelines] [My Articles]

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[Ky Nam]

I need to write this code in C++/CLI only , VS 2008 , /clr After trying C++ Interop unsuccessfully , I use p/invoke and .NET delegate

delegate bool EnumWindowsProc(IntPtr hWnd, IntPtr lParam);

[DllImport("user32", CharSet=CharSet::Ansi, SetLastError=true, ExactSpelling=true)] static int EnumChildWindows(IntPtr hWndParent, EnumWindowsProc^ lpEnumFunc, IntPtr lParam){}

bool CALLBACK EnumWindowsCallback(IntPtr hWnd, IntPtr lParam){}

void UseIt() //errors
{
EnumWindowsProc^ fp = gcnew EnumWindowsProc(EnumWindowsCallback);
EnumChildWindows(Handle, fp, IntPtr::Zero);
}

error C3350: 'EnumWindowsProc' : a delegate constructor expects 2 argument(s) error C3867: 'EnumWindowsCallback': function call missing argument list; use '&EnumWindowsCallback' to create a pointer to member I can't understand

[George L Jackson]

// Delelgate
delegate bool EnumWindowProc(IntPtr hWnd, Int32 lParam);
 
// Global callback function
bool GlobalCallback(IntPtr hWnd, Int32 lParam)
{
	// ...
	
	return true;
}
 
DllImport("User32.DLL")]
public static extern void EnumWindows(EnumWindowProc callback, Int32 lParam);
 
// Your code ...
 
// Using global function syntax for creating delegate
EnumWindowProc^ ewp += gcnew EnumWindowProc(&GlobalCallback);
 
// ,,,
 
// Invoke Delegate
EnumWindows(ewp, 0);

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