How do you call this relation between 2 .c files?

Question

I'm a bit confused, I haven't been doing C since years and I'm starting with it right again. One thing I'm not clearly sure is the relation of two files that call each others function, example:

testa.c :

int main (void)
{
    callTheOtherFunction();
    return 0;
}

and the other file

testb.c

callTheOtherFunction(){
//do some stuff
}

now my "makefile" looks like

gcc -o test ./testa.c ./testb.c

What does it mean? Is callTheOtherFunction now part of testa.c, like both files have been merged? Or has it something to do with inheritance ? Is callTheOtherFunction now a global function, or how would you call it?

I need to draw an UML diagram out of it, that's why I need the expression for that case.

Answer 1

The source files are never "merged". What happens is that during compilation phase two object files will be produced - one for each source file and later during linking phase the two object files will be linked(and also linked with some implicit system libraries) producing an executable.

Answer 2

The two files will be compiled to object code by your compiler, then the linker will generate a single executable from the object files. It is, as you say, like the two files have been merged.

callTheOtherFunction will be accessible from anywhere (I suppose you would call that a global function) as you did not mark its definition static .

As a side note, you should probably get a compiler warning from that compilation as you do not have a declaration of callTheOtherFunction in testa.c .