Question

So I get the point of headers vs source files. What I don’t get is how the compiler knows to compile all the source files. Example:

example.h

#ifndef EXAMPLE_H
#define EXAMPLE_H

int example(int argument); // prototype

#endif

example.c

#include "example.h"

int example(int argument)
    {
    return argument + 1; // implementation
    }

main.c

#include "example.h"

main()
    {
    int whatever;
    whatever = example(whatever); // usage in program
    }

How does the compiler, compiling main.c, know the implementation of example() when nothing includes example.c?

Is this some kind of an IDE thing, where you add files to projects and stuff? Is there any way to do it “manually” as I prefer a plain text editor to quirky IDEs?

Answer 1

Yes, you have to tell the compiler (usually through a makefile if you’re not using an IDE) which source files to compile into object files, and the compiler compiles each one individually. Then you give the linker the list of object files to combine into the executable. If the linker is looking for a function or class definition and can’t find it, you’ll get a link error.