Question

I think that this is valid code in MSVC:

MyClass* pMc = &MyClass();

However, when I try to do the same thing with primitive data-types I’m getting a compilation error.

int* pInt = &int();

Error:

error C2101: '&' on constant

I have 3 questions:

1. Why does int() give me a constant?
2. Why does error C2101 exists in the first place? what’s wrong with getting the address of a constant?
3. Is there a way I could declare int (or other primitive) references that point to temporary objects? (that is, without creating a local variable first)

About the 3rd question:

I do not want to do something like this:

int i = int();
int* pInt = &i;

If I’m working with references to local objects (the reasons why are irrelevant), I don’t want to have to declare each and every object twice. It’s tedious, annoying and the names would be really confusing.

Answer 1

I don’t know the answer to 1 (I think the error is wrong, because I’m pretty sure int() is not a constant), but

(2) Taking the address of a temporary is illegal. Your code shouldn’t compile but it does because of a nonstandard MSVC++ extension.

(3) Yes, use rvalue-references or const lvalue-references:

const int& tmp = int();
int&& tmp = int(); // same as former but isn't const

The lifetime of the temporary will be prolonged until the reference goes out of scope.

However, I hope you have a good reason for using one of the two above rather than

int tmp;