On Jun 13, 11 07:16, Jonathan M Davis wrote:
On 2011-06-12 15:39, Loopback wrote:
Hi!
Let me begin by saying, that I haven't used Usenet newsgroup at all, so
please excuse me for any errors or misunderstandings of the guidelines.
I recently begun programming a win32 application though I instantly got
stuck with a problem. As you might know, win32 applications require that
you define the WindowProc function for processing window messages.
I've used a object-oriented approach for this, and that requires that
you declare the WindowProc function as static, and bind your own class
(hWnd) to GWL_USERDATA, to be able to call your own, class defined,
message handler (WindowProc). To do this, you have to access the two
functions GetWindowLong and SetWindowLong.
For some reason, these functions do not exist in the windows module
(std.c.windows.windows), neither does the GWL_USERDATA constant.
To solve this I've used this alternative code:
extern (Windows)
{
int GWL_USERDATA;
LONG SetWindowLong(HWND, int, LONG);
LONG GetWindowLong(HWND, int);
}
When I then try to compile this application, the GWL_USERDATA constant
compiles without any errors, but the Get-/SetWindowLong produces linker
errors.
To solve the linker errors, I checked which library they were contained
in, on MSDN it said User32.lib. Therefore I linked to this library -
without any success.
So to summarize, how do I solve these linker errors:
Error 42: Symbol Undefined _SetWindowLong@12
Error 42: Symbol Undefined _GetWindowLong@8
Sorry for such a long message!
Any help is greatly appreciated!
I believe that you need extern(C) around those functions. They're C functions,
not D functions.
- Jonathan M Davis
extern(Windows) is correct since they have WINAPI calling convention.
The problem is their actual names are Get/SetWindowLongW/A...
