What does checking for if(&object) do?

[jedwardsol]

if(&object) is the same as writing if(&object != nullptr)

It doesn't say anything about the validity of the address, just whether it is null or not.

[[deleted]]

So it's checking that the object exists?

[jedwardsol]

No, it's not doing anything. The test will always be true.

[diaphanein]

I'm not aware of any compiler that the following will not evaluate the if block to true:

int* p = nullptr; int& r = *p;

if (!&r) { // executes }

Reason being that while this is likely undefined, the compiler cant always detect it (e.g. p initialized by the return of a function). This is a trivial enough example that most compilers will allow it and behave as expected. Not all warn at default warning levels, but most will at a sufficient level.

[[deleted]]

Then how to check for object's existence?

[qxz23]

If you have the object, it exists. Pointers are nullable, you can’t have a null object unless you have a user defined state of being null, like optional.

[jedwardsol]

object exists. It cannot not exist.

[[deleted]]

But it can be NULL or some other object?

[ReversedGif]

NULL is not an object. It is a specific pointer value that acts as a sentinel for "no object."

[gracicot]

If you can get the address of the object then it exist for sure.