How can i build my own printf in C?

Question

Do you know how to build your own printf or other functions like scanf or puts ect..?
or do you have any source that can help like online courses or books that talks only about rebuilding build-in C functions .

Answer 1

check that out
https://code.woboq.org/userspace/glibc/stdio-common/printf.c.html

Answer 2

You can refer file handling concepts in c for stdin and stdout