Question

I have a method:

odp(foo& bar);

I’m trying to call it:

foo baz;
odp(&baz);

I get a compiler error:

error C2664: "odp" cannot convert parameter 1 from 'foo *' to 'foo &'

What am I doing wrong? Aren’t I passing in a reference to baz?

UPDATE: Perhaps I have a misconception about the relationship between pointers and references. I thought that they were the same, except references couldn’t be null. Is that incorrect?

Answer 1

When you apply the unary & operator to an object, you get a pointer to that object, not a reference. You need a reference in this case. In order to initialize a reference parameter, you don’t need to apply any operators at all: an lvalue object can immediately be used by itself to initialize a reference of the appropriate type.

The informal synonymity between the notions of “pointer” and “reference” (as in “pass by pointer” and “pass by reference”) is specific to C language. But in C++ they mean two completely different things.