Should preprocessor instructions be on the beginning of a line?

Question

A while ago I have discovered an (rather ancient) C Compiler, which scanned macros this way (Pseudo code):

 if line.startswith(\"#include\") or line.startswi         


        

Answer 1

from gcc C preprocessor documentation:

Preprocessing directives are lines in your program that start with #'. Whitespace is allowed before and after the#'.