Where are the library function definitions located?

Hi friends,
I hope everyone is doing fine. I have this confusion, hope you can help me out with it. The header files contain only function prototypes. Where are the function definitions located. For example, if I would like to see how printf works, where can I see its definition, stdio.h only tells us about the prototype.

Looking forward to your wonderful replies!

Thanks in advance!

They are usually not kept around as source code, but in the binary library files libc.so and/or libc.a.

If you want to see the code with your own eyes, grab the source code of any implementation of the standard C library, such as the GNU Glibc ( GLIBC, the GNU C Library ) or one of those that are maintained by the some BSD project (like the FreeBSD implementation).