stdafx. H introduction and function

Reprint ：stdafx.h Introduction and function _Petrichor^ The blog of -CSDN Blog _stdafx.h

a key ：

1.#include “stdafx.h”. All code in front of it will be ignored , So other header files should be included after this line

2.Stdafx.h” Is a precompiled Title , It includes documents of the standard system , Include files and project specific files , These files are often used , But it's rarely modified . This reduces compilation time and unnecessary processing .

3.stdafx.h It exists to improve the compilation speed .