PRB: MFC Control Panel Applet Shows ODBC Icon in Control Panel (151034)
The information in this article applies to:
- The Microsoft Foundation Classes (MFC), when used with:
- Microsoft Visual C++, 32-bit Editions 4.0
- Microsoft Visual C++, 32-bit Editions 4.1
This article was previously published under Q151034 SYMPTOMS
The MFC Control Panel applet displays the ODBC icon on the Control Panel
with the functionality of the ODBC data source setup Control Panel applet.
The NTCPLAPP MSDN sample exhibits this behavior.
CAUSE
The applet entry-point function, CPlApplet(), exported by the MFC control
applet, is resolved to the function exported from ODBCCP32.LIB rather than
the function exported from the project.
RESOLUTION
If you are not using any of the functions exported by ODBCCP32.LIB, then
select the Input category in the Project Settings for the linker, and
specify "odbccp32.lib" in the "ignore libraries" field. This is equivalent
to adding /nodefaultlib:"odbccp32.lib" in the linker command line.
However, if you have to link in the ODBCCP32.LIB file, then close the
workspace, open the .mak file for the project as text, and add
"odbccp32.lib" to the linker dependency line as shown in the example below.
In the case of the NTCPLAPP sample, you should see lines similar to the
following:
"$(OUTDIR)\MyCplApp.cpl" : "$(OUTDIR)" $(DEF_FILE)$(LINK32_OBJS)
$(LINK32) @<<
$(LINK32_FLAGS) $(LINK32_OBJS)
These lines are the linker dependency and command line. Each target has
these lines. Modify the last line as follows:
$(LINK32_FLAGS) $(LINK32_OBJS)odbccp32.lib
This ensures that functions exported by the ODBCCP32.LIB file are searched
last while linking. The CPlApplet is resolved to the one in your code
because the .OBJ files are searched prior to the import libraries. If there
are multiple targets, the modification needs to be made for all the
targets.
STATUS
This behavior is by design.
MORE INFORMATION
Every Control Panel application must export the standard entry-point
function CPlApplet that is called by Control Panel in various situations.
When you include AFXDB.H in your project, MFC pulls in the ODBCCP32.LIB
file through a #pragma comment(). This is the import library for the ODBC
installation DLL that also exports CPlApplet. The linker resolves the
CPlApplet function from the ODBCCP32.LIB rather than from your object
files. Since CPlApplet resolves to the one in ODBCCP32.LIB, your Control
Panel applet acts as another ODBC Control Panel applet.
This behavior occurs in an Control Panel applet based on an appwizard-
generated regular DLL project that includes AFXDB.H in STDAFX.H by default.
REFERENCES
Visual C++ Books Online and the Windows SDK documentation.
| Modification Type: | Major | Last Reviewed: | 10/24/2003 |
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| Keywords: | kbDatabase kbprb KB151034 |
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