What is stdafx h used for in Visual Studio

Question

A file named stdafx h is automatically generated when I start a project in Visual Studio 2010  I need to make a cross-platform C   library  so I don t can t use this header file   What is stdafx h used for  Is it OK that I just remove this header file

User · Answer

It s a  precompiled header file  -- any headers you include in stdafx h are pre-processed to save time during subsequent compilations  You can read more about it here on MSDN   If you re building a cross-platform application  check  Empty project  when creating your project and Visual Studio won t put any files at all in your project

User · Answer

Stdafx h  is a precompiled header It include file for standard system include files and for project-specific include files that are used frequently but are changed infrequently which reduces compile time and Unnecessary Processing   Precompiled Header stdafx h is basically used in Microsoft Visual Studio to let the compiler know the files that are once compiled and no need to compile it from scratch  You can read more about it  http   www cplusplus com articles 1TUq5Di1   https   docs microsoft com en-us cpp ide precompiled-header-files view vs-2017

User · Answer

All C   compilers have one serious performance problem to deal with  Compiling C   code is a long  slow process   Compiling headers included on top of C   files is a very long  slow process  Compiling the huge header structures that form part of Windows API and other large API libraries is a very  very long  slow process  To have to do it over  and over  and over for every single Cpp source file is a death knell   This is not unique to Windows but an old problem faced by all compilers that have to compile against a large API like Windows   The Microsoft compiler can ameliorate this problem with a simple trick called precompiled headers  The trick is pretty slick  although every CPP file can potentially and legally give a sligthly different meaning to the chain of header files included on top of each Cpp file  by things like having different macros  define d in advance of the includes  or by including the headers in different order   that is most often not the case  Most of the time  we have dozens or hundreds of included files  but they all are intended to have the same meaning for all the Cpp files being compiled in your application   The compiler can make huge time savings if it doesn t have to start to compile every Cpp file plus its dozens of includes literally from scratch every time   The trick consists of designating a special header file as the starting point of all compilation chains  the so called  precompiled header  file  which is commonly a file named stdafx h simply for historical reasons   Simply list all your big huge headers for your APIs in your stdafx h file  in the appropriate order  and then start each of your CPP files at the very top with an  include  stdafx h   before any meaningful content  just about the only thing allowed before is comments    Under those conditions  instead of starting from scratch  the compiler starts compiling from the already saved results of compiling everything in stdafx h   I don t believe that this trick is unique to Microsoft compilers  nor do I think it was an original development   For Microsoft compilers  the setting that controls the use of precompiled headers is controlled by a command line argument to the compiler   Yu  stdafx h   As you can imagine  the use of the stdafx h file name is simply a convention  you can change the name if you so wish   In Visual Studio 2010  this setting is controlled from the GUI via Right-clicking on a CPP Project  selecting  Properties  and navigating to  Configuration Properties C C   Precompiled Headers   For other versions of Visual Studio  the location in the GUI will be different   Note that if you disable precompiled headers  or run your project through a tool that doesn t support them   it doesn t make your program illegal  it simply means that your tool will compile everything from scratch every time   If you are creating a library with no Windows dependencies  you can easily comment out or remove  includes from the stdafx h file  There is no need to remove the file per se  but clearly you may do so as well  by disabling the precompile header setting above

User · Answer

I just ran into this myself since I m trying to create myself a bare bones framework but started out by creating a new Win32 Program option in Visual Studio 2017    stdafx h  is unnecessary and should be removed   Then you can remove the stupid  stdafx h  and  stdafx cpp  that is in your Solution Explorer as well as the files from your project   In it s place  you ll need to put   include  lt Windows h gt    instead

[visual-studio] What is "stdafx.h" used for in Visual Studio?

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