Passing data between functions and main

[Behnood]

If I have declared variables in another function such as main, how do I access them in another function? (Instructor does not allow global variables)

[laserlight]

100 bottles of beer on the wall, 100 bottles of beer, take one down pass it around, 99 bottles of beer on the wall....

void f(int& x) {
	// ...
}

int main() {
	int x = 0;
	f(x);
}

though here I'm taking your "access them in another function" rather literally by passing by reference.

[exterminator]

What are different methods to pass parameters to functions?