Precompiled Header Files

Article
05/26/2017

The new home for Visual Studio documentation is Visual Studio 2017 Documentation on docs.microsoft.com.

For the latest documentation on Visual Studio 2017, see Precompiled Header Files on docs.microsoft.com. These files are used to build a precompiled header file Projname.pch and a precompiled types file Stdafx.obj.

These files are located in the Projname directory. In Solution Explorer, Stdafx.h is in the Header Files folder, and Stdafx.cpp is located in the Source Files folder.

File name Description

Stdafx.h An include file for standard system include files and for project-specific include files that are used frequently but are changed infrequently.

You should not define or undefine any of the _AFX_NO_XXX macros in stdafx.h; see the Knowledge Base article "PRB: Problems Occur When Defining _AFX_NO_XXX". You can find Knowledge Base articles in the MSDN Library or at https://support.microsoft.com/.

Stdafx.cpp Contains the preprocessor directive #include "stdafx.h" and adds include files for precompiled types. Precompiled files of any type, including header files, support faster compilation times by restricting compilation only to those files that require it. Once your project is built the first time, you will notice much faster build times on subsequent builds because of the presence of the precompiled header files.

File name	Description
Stdafx.h	An include file for standard system include files and for project-specific include files that are used frequently but are changed infrequently. You should not define or undefine any of the _AFX_NO_XXX macros in stdafx.h; see the Knowledge Base article "PRB: Problems Occur When Defining _AFX_NO_XXX". You can find Knowledge Base articles in the MSDN Library or at https://support.microsoft.com/.
Stdafx.cpp	Contains the preprocessor directive `#include "stdafx.h"` and adds include files for precompiled types. Precompiled files of any type, including header files, support faster compilation times by restricting compilation only to those files that require it. Once your project is built the first time, you will notice much faster build times on subsequent builds because of the presence of the precompiled header files.

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Precompiled Header Files

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