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Excluding Files When Dependency Checking

Adding an include file to one of your source code files creates a dependency. The source file depends on the include file. During the build process, the project system checks to see if an include file has changed and if the source file needs to be recompiled. Some include files never change, and you can reduce build time by eliminating dependency checking for those files.

A file called SYSINCL.dat file, which you create, lists the directories that are excluded from dependency checking. Any file in a specified directory or one of its subdirectories will be excluded. Visual C++ reads SYSINCL.dat when you start the product.

You can put a SYSINCL.dat file in Local Settings\Application Data\Microsoft\VisualStudio\version (for example, in C:\Documents and Settings\username).

In addition to being able to specify directories in which no file will ever be checked for dependencies, Visual C++ will never check dependencies for any file residing in or under the version subdirectory.

To exclude files from dependency checking

  1. Add directory names (using full, absolute paths) one per line, to SYSINCL.dat.

  2. Exit the development environment.

  3. Restart the development environment.

  4. Click Rebuild for changes to take effect.


Excluding dependencies does not increase the speed of the Rebuild command because no dependency checking occurs with Rebuild.