[NumLock]

Код:

LRESULT CALLBACK KeyboardProc(
    int code,	// hook code
    WPARAM wParam,	// virtual-key code
    LPARAM lParam 	// keystroke-message information
   );

lParam

Specifies the repeat count, scan code, extended-key flag, context code, previous key-state flag, and transition-state flag. This parameter can be a combination of the following values:

Value Description
0-15 Specifies the repeat count. The value is the number of times the keystroke is repeated as a result of the user's holding down the key.
16-23 Specifies the scan code. The value depends on the original equipment manufacturer (OEM).
24 Specifies whether the key is an extended key, such as a function key or a key on the numeric keypad. The value is 1 if the key is an extended key; otherwise, it is 0.
25-28 Reserved.
29 Specifies the context code. The value is 1 if the ALT key is down; otherwise, it is 0.
30 Specifies the previous key state. The value is 1 if the key is down before the message is sent; it is 0 if the key is up.
31 Specifies the transition state. The value is 0 if the key is being pressed and 1 if it is being released.