Difference between variable declarations...

[pmatos]

Hi all,

What's the difference between:
int& i;

and

int i;

?

Cheers,

Paulo Matos

 

[Rolf Magnus]

Hi all,

What's the difference between:
int& i;

and

int i;

?

The former is a reference to an integer, the latter is an integer.

 

[pmatos]

Got it, thanks. 5.5 of C++PL.

 

[Sharad Kala]

The former is a reference to an integer, the latter is an integer.

Also former is not legal C++, a reference has to be initialized for sure.

Sharad

 

[Victor Bazarov]

Also former is not legal C++, a reference has to be initialized for sure.

It us legal if it appears inside a class definition.

V

 

[Sharad Kala]

sure.

It us legal if it appears inside a class definition.

Yes.
To OP: Even then you need to bind the reference in the initializer list.

Sharad

 

[Rolf Magnus]

Also former is not legal C++,

Wrong. The following should compile:

struct X
{
X(int& i) : i(i) {}

int& i;
};

int main()
{
int i = 3;
X x(i);
}

a reference has to be initialized for sure.

True.

 

[Sharad Kala]

Wrong.

Not totally wrong.
int main()
{
int& i; // Not legal
}

Given the context in which OP asked the question, it seemed that it was not
in a class definition. The point I was trying to stress was that you cannot
leave the reference uninitialized.

Sharad

 

[Rolf Magnus]

Not totally wrong.
int main()
{
int& i; // Not legal
}

Well, can you name one language construct that can be used _everywhere_ in a
program?

Given the context in which OP asked the question, it seemed that it was
not in a class definition.

Actually, I don't see any context.

The point I was trying to stress was that you cannot leave the reference
uninitialized.

And I agreed to that.

 

[Alf P. Steinbach]

* Rolf Magnus:

Actually, I don't see any context.

Note the semicolon at the end in the Original Posting:

int& i;

This is only valid in a class definition.

But since the question was what does it mean, it probably doesn't
imply very much about context...

 

[pmatos]

* Rolf Magnus:

Note the semicolon at the end in the Original Posting:

int& i;

This is only valid in a class definition.

But since the question was what does it mean, it probably doesn't
imply very much about context...

Indeed, I didn't want to know about context specific questions but I
didn't know it had to be initialized until before reading section 5.5
of C++PL. Anyway, I already understood what it is for.

Thanks a lot people and don't get mad about context specific
questions...

Cheers,

Paulo Matos

 

[Rolf Magnus]

Thanks a lot people and don't get mad about context specific
questions...

Nah, we don't. We're just nitpicking. That's what makes us nerds.