1 ipch文件夾
用來加速編譯，里面存放的是precompiled headers，即預編譯好了的頭文件。
頭文件也是需要編譯的，比如需要處理#ifdef，需要替換宏以及需要include其它頭文件。
將一些常用的但是不經常修改的頭文件編譯好放在一個文件中，后面的編譯就直接用這個頭文件而不用重新編譯。
2 sdf文件和opensdf文件
sdf文件是vs用於intellisense的。
https://msdn.microsoft.com/zh-cn/library/hcw1s69b.aspx
2.1 list class members
鼠標放在某個class上，會自動顯示這個class有哪些members。
2.2 顯示某個函數的完整參數信息，這樣方便自己編碼
2.3 自動完成單詞
3 sln文件
解決方案文件。
4 suo文件
https://shemeerns.com/2014/04/04/the-solution-user-options-suo-file-in-visual-studio/
What is Solution User Options (.suo) file
The solution user options (.suo) file is a structured storage, or compound, file stored in a binary format. This file is used to store user preference settings, and is created automatically when Visual Studio saves a solution.
Location of .suo file
The .suo file will be saved in the folder where your Solution (.sln) file exists. You might wanted to set true for “Show Hidden Files and Folder” in “Folder Options” as .suo file is default by hidden.
What informations are saved in my .suo file
This file is used by Visual Studio to store user/solution specific information such as Opened Files, Expanded Nodes in the Solution Explorer, Opened Tool Windows and its Positions, User Tasks, Breakpoints, Start-up Project, Contents of Watch window, Whether the project is loaded/unloaded etc. The same file is used by Visual Studio Addins (VSPackages) to persist information that are specific to that solution/user.
.suo file and Source Control
Adding user specific information to source control is not a good idea. Most of the code versioning control ignores .suo file by default. If included, the developer, who checks out the latest .suo file, will loose all his personal settings which is stored in the local .suo file.
Visual Studio performance and .suo file
If the size of .suo file is too large then it can affect the performance of Visual Studio. Deleting the .suo file will boost the performance.
Deleting .suo file
Visual Studio creates a new file with the .suo file extension as soon as you open again the solution. But once the file with the .suo file extension is deleted, any of your existing solution user-specific settings will be lost.