C inline functions [duplicate]

As far as i know, inline functions in C work pretty the same way as in C++ when used in single translation unit and there's no need to dive into extern inline difficulties in such a case. However, the following program including three files seems not to compile in C and I am struggling to figure out why.

f.h

int f(); inline int g(); 

f.c

#include "f.h" inline int g() { return 5; } int f() { return 3 + g(); } 

main.c

#include "f.h" #include <stdio.h> int main() { printf("%d", f()); return 0; } 

The linker

tells that there is an undefined reference to g. However, as g is used only in f.c file, I can not define where the problem lies exactly.