callbyreference between functions

I have the following code:

void zufallszahl()
{
    int zufallbonus
	srand(time(0));
	zufallbonus = (rand () % 5);
}

void berechnen(int *p_bonus)
{
	zufallszahl();
	spieler.energie =+ *p_bonus;

}

I want *p_bonus(line 10) to point to zufallbonus(line 3). How can I achieve that with two different functions? So far I only had to deal with variables, which where defined in the main-function and I would simply point to them with a function. This time the variables are in two seperate functions.

Edit: callbypointer ofc