Thread: standard functions' definitions

Hi,

I'm wondering where the standard C functions, like printf, etc .. are defined.
I know their prototypes/declarations are in stdio.h and other standard headers.

Will I have to look into the my compiler's (gcc) src in order to find them? If so, where specifically ?

Thanks in advance.

Thanks for replies.
I've found the libraries in /usr/src/lib/libc in FreeBSD.