How properly hook WM_COMMAND

Question

I\'m trying to hook a button click in a mfc window.And I used WM_COMMAND and WM_NOTIFY.For test, if the button is clicked, the hook must create a messagebox. The problem is

Answer 1

The lParam for a WH_CALLWNDPROC hook is of type CWPSTRUCT. Your CallWndProc should look like this:

// ...
const CWPSTRUCT& cwps = *(CWPSTRUCT*)lParam;
switch ( cwps.message ) {
case WM_COMMAND:
    MessageBox( ... );
    break;
// ...