Path: utzoo!utgpu!watserv1!watmath!att!dptg!ulysses!andante!mit-eddie!media-lab!snorkelwacker!usc!elroy.jpl.nasa.gov!ncar!mephisto!mcnc!rti!bcw
From: bcw@rti.rti.org (Bruce Wright)
Newsgroups: comp.windows.ms
Subject: Re: MessageBox problem
Summary: MessageBox problems
Message-ID: <4060@rtifs1.UUCP>
Date: 10 Sep 90 05:30:04 GMT
References: <1990Sep9.224303.10981@bdmrrr.bdm.com>
Organization: Research Triangle Institute, RTP, NC
Lines: 40

In article <1990Sep9.224303.10981@bdmrrr.bdm.com>, davis@bdmrrr.bdm.com (Arthur Davis x4675) writes:
> Someone mentioned having a problem with garbled strings in a
> MessageBox call; i.e. MessageBox (hDlg, "abc", "xyz", MB_OK)
> produces garbage on the display.
> 
> [...]
>
> Try this:
> 
> MessageBox (hDlg, (LPSTR) "abc", (LPSTR) "xyz", MB_OK);
> 
> This will force the pass of a FAR or long address and should solve your
> problem.

If you are using the Microsoft SDK, the windows.h file defines
MessageBox as:

	int FAR PASCAL MessageBox (HWND, LPSTR, LPSTR, WORD);

Unless your C compiler has some serious problems with parameter
definitions, you shouldn't need to use the (LPSTR) in the call
to MessageBox.

It's possible that the strings are getting clobbered by a
runaway pointer in another part of the program.

But the fact that the MessageBox call is using an hDlg handle
makes me wonder if the original author was calling this from
a dialog box window.  If so, one of the first things to look
for would be to see if a MakeProcInstance call was made for
the dialog box procedure, and if the procedure itself was
exported in the .DEF file.  Failure to do either of these
can cause serious problems that can sometimes show up in
flakey ways.  Also check for whether the application has
any memory or resource leaks (allocating memory or resources
without releasing them);  this can also sometimes cause funny
behavior (including screen garbage, depending on what the
application is doing and the mode Windows was started in).

					Bruce C. Wright