Memcmp implementation without libraries?

Question

C++ / C#

I write low-level code in C.
I urgently needed memcmp, but I can't use the libraries.

How can memcmp be implemented in C without libraries and assembler inserts?

Answer 1

Look for different implementations on the Internet, even Wikipedia has implementations.
here is an implementation example

Answer 2

Why is for (..) not suitable for comparing char by address range?

Answer 3

Take the source from libc, drag it to your project.