Thread: preprocessor

Why does the following line of code generate error as " pasting / and / doesnot generate a valid preprocessing token"? Can someone please help

Code:

#define comment /##/
   int main()
  {
    comment printf("hello");
    return 0;
   }

## is an operator for the preprocessor. It glues tokens together. See C preprocessor - Wikipedia, the free encyclopedia

Also, by the time preprocessing happens, comments are removed.

They are not valid tokens.

Token-Pasting Operator (##) (C/C++)

Also as whiteflags says, comments are removed during pre-processing (http://www.jncasr.ac.in/ccms/esc/programme/day8.pdf [search for "comment removal" or "Preprocessing"]). So that really doesn't make sense.