Where do definitions for standard function descriptions come from?

Question

C++ / C#

Good afternoon
As I understand it, the standard functions have been compiled for a long time and are waiting until they are connected in some program by extern in the header. The question is - how does the compiler understand where to get function definitions and how to achieve the same result in order to translate the source code into object code once and not tell the compiler again, but to include the necessary files itself?

Answer 1

The C and C++ standard libraries are included by default, you don't need to specify any options to the compiler for this. On the contrary, it takes some effort to get rid of it.