Reference: vs view macro expand VC view macro definition
Macros can often bring us great convenience in our code, but some macros can cause unexpected errors. You can view the root cause of macro errors by viewing the macro expansion. VS2008 does not save the preprocessed file information for compilation, and the macro expansion information is in the precompiled stage. As shown below:
Project Properties--"Configuration Properties--"c/c++--"Preprocessor--"Generate preprocessing files, the default "No" is not to generate precompiled files. The generated precompiled file is the .i file under the project file . If you want to generate this file, you can select the option "Generate preprocessing file" "with line number (/P)" or "without line number (/EP /P)" )”