1) If understand correctly from tutorials in order to inline a function you add the inline keyword and nothing else. Is this correct? Is this the same for C89 and C99?
2) Declaring inline a function from another file is done with the same way? There is a difference in C89 and C99 when using extern and inline, and thus an option in gcc to choose, but I can't understand the difference no matter how many times I read it. I feel kind of stupid