Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!decwrl!parc!rybicki
From: rybicki@parc.xerox.com (Adam Rybicki)
Newsgroups: comp.windows.ms.programmer
Subject: Re: Passing data to a DLL; strange problem!
Message-ID: <1991Apr22.185848.21897@parc.xerox.com>
Date: 22 Apr 91 18:58:48 GMT
References: <1991Apr22.173022.8930@javelin.sim.es.com>
Sender: news@parc.xerox.com
Organization: Xerox PARC
Lines: 54

In article <1991Apr22.173022.8930@javelin.sim.es.com> lwallace@javelin.sim.es.com (Raptor) writes:
>(One wonders if I'll ever find a Windows technique that works the
>first time I try it...)
>
>I've recently broken my application up into a DLL and a main program
>module.  One of the functions I've exported to the DLL needs to
>enumerate top-level windows, so I want to pass it my application's
>top-level window handle to feed FindWindow().
[...]


>HWND ParentHandle;
>...
>void FAR PASCAL TxferParentHandle(HWND hwnd)
>{
>ParentHandle = hwnd;
>}
>
>This is how I call it from my main module:
>
>HWND ParentHandle;
>...
>WinMain(...)
>{
>...
>TxferParentHandle(hwnd);
>}
>
>
>
>The DLL's copy of ParentHandle remains 0.  hwnd is set as expected.
>It was baffling to execute the assignment statement in CodeView and
>see that it doesn't work!
>
>I have discovered, through CodeView, that the address of ParentHandle
>in the DLL is in a different segment from that shown in DS and SS
>(which are equal):
>
[...]
>Has anyone encountered this?  Any suggestions?
>-- 

Yes, I have...  There is no problem with your code.  You have two
variables with the same name--ParentHandle.  CodeView gets confused
and displays the contents of the application's ParentHandle, not the
DLL's.  Try using a different variable name.


>            Lynn Wallace           |           I do not represent E&S.
>Evans and Sutherland Computer Corp.|   Internet: lwallace@javelin.sim.es.com
>      Salt Lake City, UT 84108     |           Compu$erve:  70242,101
>	      Revenge is a dish best not served at all.

					----- Adam Rybicki -----