Visual C++ Vers 2.0 README.WRI, Part 10 Miscellaneous Notes

• Microsoft Visual C++, 32-bit Edition, version 2.0 on the following platform: x86

SUMMARY

The following is based on the Visual C++ version 2.0 README.WRI file:

Link Libraries for MFC Projects

With the Microsoft Foundation Class Library (MFC) version 3.0 in Visual C++ version 2.0, it is no longer necessary to specify standard libaries for MFC applications. The MFC header files now generate /defaultlib directives to link the correct variant of the MFC library, and to link WINDOWS.H and other system header files as necessary.

Having standard Link Input files specified in the MFC .MAK files does not usually cause a problem. However, if you change from "Use MFC in a Static Library" (the default setting) to "Use MFC in a Shared Dll (mfc30(d).dll)" (in the Microsoft Foundation Classes box on the General tab of the Project Settings dialog box), you will get link errors such as the following:

   mfc30d.lib (MFC30D.DLL) :
       error LNK2005: ?messageMap@CWinApp@@1UAFX_MSGMAP@@B (protected:
          static
       struct AFX_MSGMAP const CWinApp::messageMap) already defined in
       nafxcwd.lib(appcore.obj)

To avoid this problem, remove all libraries from the Object/Library Modules box of the Input category on the Link tab of the Project Settings dialog box.

Converting Visual C++ Version 1.5 Non-MFC Sample Programs

Converting applications developed with Visual C++ versions 1.0 or 1.5 may not automatically add the appropriate library files to the linker command line. For example, the SORTDEMO sample is not an MFC project and is not marked as an MFC project in the corresponding Visual C++ version 1.5 makefile. However, after Visual C++ version 2.0 converts the project, it is marked as an MFC project and no Windows libraries are included on the linker command line. This causes unresolved externals when the project is built. To work around this problem, choose "Not Using MFC" in the General tab of the Project Settings dialog.

MFCANS32 and MFCUIX32 Sample Directories

There are two DLLs that are internal to the Microsoft Foundation Class Library’s OLE implementation: MFCUIx32.DLL and MFCANS32.DLL. Most OLE applications must ship these two DLLs. See the REDISTRB.WRI file in the \MSVC20\REDIST subdirectory for more information on these binary files.

Source code for both of these DLLs is provided in the \MSVC20\SAMPLES\MFC\MFCUIX32 and \MSVC20\SAMPLES\MFC\MFCANS32 subdirectories. The source is provided to help debug your application. See the MAKEFILE for each of these DLLs for information on building the debug version.

Adding ToolTips to Your Application

ToolTips are not documented in the Books Online manuals. Each toolbar button with a ToolTip maps to a menu resource ID name. To prepare your application for using ToolTips, use the menu editor to select the command to which the desired toolbar button is mapped, and expose the Property Page with ALT+ENTER. In the Prompt: field, enter the text string that should appear on the status bar when the menu command is selected. To create the ToolTip text, enter "\n" at the end of the Status Bar prompt, followed by the desired ToolTip text. An example for the File-New toolbar button could be:

Prompt: Creates a new document\nNew source file

Any application generated by AppWizard follows this convention and can be used to demonstrate and understand the feature.

The string editor can also be used to create the Prompt: string, but it is more direct and easier to use the menu editor.

Multithread Programming

If the value of a variable can be modified by another thread or by the operating system and your program depends on this behavior, you should declare the variable as volatile. Without the volatile keyword, the optimizing compiler may enregister a copy of this variable, leading to unexpected behavior.

Double Quotation Marks in Makefiles

Use of double quotation marks (") as part of a target name is not supported (as in: MyTarget "TARGET").

Makefiles containing double quotation marks within a target name may be unrecognizable to the development environment.

64-bit Integers

In addition to the __int8, __int16, and __int32 "sized integer" support documented in the C Language Reference and C++ Language Reference, this Visual C++ version 2.0 release provides support for 64-bit integers. To declare a 64-bit integer, use the __int64 keyword.

Using printf and scanf with 64-bit Integers

You can use the __int64 data type with the printf and scanf function families.

A printf format specification, which consists of optional and required fields, has the following form:

%[flags] [width] [.precision] [{h | l | I64 | L}]type

A scanf format specification, which also consists of optional and required fields, has the form:

%[*] [width] [{h | l | I64 | L}]type

The I64 optional prefix to the type specifier indicates that the corresponding argument is a 64-bit integer. To specify _int64, you can use the size prefix I64 with the type specifier d, i, o, u, x, or X. The type prefix I64 is a Microsoft extension and is not ANSI-compatible. For more information, see printf and scanf in the Run-Time Library Reference.

Writing 32-bit ODBC Applications

An update to ODBC version 2.0 is required to build ODBC applications for DBCS-enabled versions of Windows NT (including Windows NT/Japanese) and Windows 95. At the time Visual C++ version 2.0 was released, an update to ODBC version 2.0 was not available. The retail version will be distributed on the Microsoft Developer Network Development Library Level 2 CD-ROM when it is available.

ODBC Classes and Threads

Because the Microsoft Foundation Class libraries that utilize ODBC cannot ensure that all ODBC components and drivers are completely thread aware, these classes are not thread-safe.