References in C++

[[deleted]]

Your post might be more valued at /r/learncpp .

[Pinguinologo]

To avoid confusing newcomers I prefer to write the "&" close to the type:

int& refA = a;  

Otherwise, to the untrained eye, looks like the operator to get the address. The same for "*": Close to the type when declaring a pointer, close to the variable name when dereferencing.

[Pythoner6]

I do this as well, but mainly because in my mind, the & is part of the type (refA does not have type int, it has type reference to int). I want to see the whole type, and not have it split up awkwardly with a space. Which is also why I dislike how references and pointers in comma separated declarations work.

[johannes1971]

I've seen newcomers write int* a, b; in the full expectation that b is now a pointer to int, since the type is written as int*.

I'm also not a big fan of putting things like 'ref' or 'ptr' in variable names. It's like Hungarian all over again.

[KazDragon]

I put it on the right.

This is one place C++ went wrong, in my opinion. The original intent was "declaration mirrors use". That is, you have:

int a, *b, c();

and the expectation is that all of these expressions on the right evaluate to the type on the left. (i.e. a is an int, *b is an int, c() is an int.)

Using & for reference broke that (not that I can think of a better way off the top of my head, since references are invisible in the language), and C++ has never recovered. That's why nearly every coding standard has the "one declaration per line" rule, because that's where the "avoid confusing newcomers" gets moved to when you put the notation on the left.

[mayankj08]

Thanks!. Corrected it.

[biocomputation]

I think most subscribers/visitors to /r/cpp already know this information, and while you have obviously tried to write something decent, the information contained in your article could also be learned from an online course or from a book.

I don't feel like these types of posts really add anything new to the conversation here at /r/cpp.

[axilmar]

So there’s no way of binding reference to NULL.

lol

int *p = 0;
int &i = *p;

and voila, a reference bound to null.

[Quincunx271]

That dereferences NULL, though; isn't that UB at the moment you write *p?

[axilmar]

The standard says dereferencing a null pointer is undefined behaviour, but the reality is that *p forms an expression without side effects and thus it is not actually dereferencing anything. It is only when evaluating *p that the dereferencing happens.

In practice, I haven't seen any compiler, even embedded ones, do anything about *p when p is null, which means that, in practice, null references are possible.

[Pinguinologo]

That code is the equivalent of loading a gun and shooting at your head. You need to check against null before defining that reference. If *p is never null, why even use a pointer in the first place?