说明：  预处理过程扫描源代码，对其进行初步的转换，产生新的源代码提供给编译器。可见预处理过程先于编译器对源代码进行处理
(The preprocessing process scans the source code, performs a preliminary conversion, and generates new source code for the compiler. It is evident that the preprocessing process processes the source code earlier than the compiler)