Re: what's the difference?

From:

"marcin.sfider@gmail.com" <marcin.sfider@gmail.com>

Newsgroups:

comp.lang.c++.moderated

Date:

Sun, 19 Apr 2009 17:47:45 CST

Message-ID:

<3a20e773-2421-45fc-80a5-6a8d93a74fec@r33g2000yqn.googlegroups.com>

On 17 Kwi, 22:09, Jonathan Lee <cho...@shaw.ca> wrote:

In practice, I prefer the second, pass by reference, where I have the
option. I do this for type safety. A reference cannot be null, so I
don't need to check for that (unlike a pointer). Also a reference is a
complete object. A pointer can be messed with and made to point to
something other than MyClass. A reference _is_ a MyClass.

Saying that reference cannot be null is misleading. For example:

void function(MyClass& obj) {
     obj.method();
}

MyClass* obj = nullptr;
.... // by mistake no valid address to MyClass object was assigned
.... // to obj pointer
function(*obj); // there will be no runtime check preventing creation
                 // of reference from null pointer

If there is a possibility that someone will use null pointer on
your function taking reference, you should handle this. For example:

void function(MyClass& obj) {
     assert (&obj != nullptr);
     obj.method();
}

Cheers
Sfider

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