Passing a modifiable parameter to c++ function

Question

Provided, I want to pass a modifiable parameter to a function, what should I choose: to pass it by pointer or to pass it by reference?

1. bool GetFoo ( Foo& w

Answer 1

I choose #2 because it obvious at the point of call that the parameter will be changed.

GetFoo(&var) rather than GetFoo(var)

I prefer pass by reference for just const references, where I am trying to avoid a copy constructor call.