> The preprocessor poses another major problem. The preprocessor language and the core C compiler have no knowledge of each other. They are completely separate

> The preprocessor poses another major problem. The preprocessor language and the core C compiler have no knowledge of each other. They are completely separate languages, with their own syntax, keywords, semantics, etc. "I wrote my program in C." No, you wrote your program in a custom language that only you (at most) understand, and you gave the file a .c extension.