Why can't I use //-style comments in my C code?

Question

I am using gcc (Ubuntu 4.4.1-4ubuntu9) to compile a program that I'm writing, but it seems to vomit whenever it sees a // comment in my code, saying:

interface.c :##: error: expected expression before a/a token<

Does the gcc compile mode I'm using forbid // comments?

$ gcc -g -ansi -pedantic interface.c structs.h -c -I. -I/home/me/project/h

Why?

question from:https://stackoverflow.com/questions/2223541/why-cant-i-use-style-comments-in-my-c-code

Answer 1

// comments are not allowed in old (pre 99) C versions, use /**/ (or remove the -ansi, that is a synonym for the C89 standard)