While using the CreateWindow function to create child controls inside the main window do I have to pass the main hInstance to it? I know I have to pass it while creating the main window, but what about child controls? If the answer is no, could you explain why so?
Yes you'd need to. Well dont ask me why I'm no expert in these matters. You dont need to copy the hInstace to a global variable or some such crap...a GetModuleHandle(NULL) call would give you what you need. Example:
Code:HWND button=CreateWindowEx(0,"BUTTON","Click meh!",BS_PUSHBUTTON|WS_CHILD,10,20,100,30,parentHwnd,(HMENU)cmdId,GetModuleHandle(NULL),NULL);
Last edited by the_jackass; 01-01-2015 at 10:25 AM. Reason: corrected CreateWindow call to CreateWindowEx
"Highbrow philosophical truth: Everybody is an ape in monkeytown" --Oscar Wilde
I mean to say that i have seen some example pass just NULL as that second-to-last argument, instead of hInstance or GetModuleHandle(NULL). Is there a time when we should pass an hInstance and a time when we should pass NULL?
"Is there a time when we should pass an hInstance and a time when we should pass NULL?"
Cant say. I tried with passing NULL right now and it worx. I prefer to be on the safe side though and always pass GetModuleHandle(NULL).
RegisterWindowEx() always fails when WNDCLASSEX object's hInstance is set to NULL.
"Highbrow philosophical truth: Everybody is an ape in monkeytown" --Oscar Wilde
OK. Thank you for your input.
IIRC (I remember reading it somewhere, but never confirmed if it is so) passing NULL for the hInstance is the same as passing the hInstance which is the first argument of WinMain() for the application.
It is probably not a good idea to do that if calling CreateWindow() within a DLL, since those windows need the hInstance of the DLL, not the application using the DLL. This distinction may be significant for globally registered window classes (which includes all standard buttons, widgets, etc) but not for window classes that are specific to the application or DLL.
