[q]operator & (getting address)

[Marchello]

Hi All.
I will try to explain my question on following example:

Having class CInteger (wraper on 'int' values):

class CInteger
{
public:
.....
void SetValueFromPoiner(int *new_value)
{
value = *new_value;
}
.....
private:
int value;
};

This class need an operator of getting address of 'value'.
Some like this:

CInteger A(...);
CInteger B(...);

B.SetValueFromPoiner(&A); // &A => (return &A.value).

How to write this operator ?

[Phil Endecott]

Marchello wrote:

B.SetValueFromPoiner(&A); // &A => (return &A.value).

How to write this operator ?

You cannot overload operator&. It is one of a very few operators that
cannot be overloaded.

--Phil.

[Rapscallion]

Phil Endecott wrote:

You cannot overload operator&. It is one of a very few operators that
cannot be overloaded.

Unfortunately you can. But you shoudn't!

[Shezan Baig]

Marchello wrote:

Hi All.
I will try to explain my question on following example:

Having class CInteger (wraper on 'int' values):

class CInteger
{
public:
....
void SetValueFromPoiner(int *new_value)
{
value = *new_value;
}
....
private:
int value;
};

This class need an operator of getting address of 'value'.
Some like this:

CInteger A(...);
CInteger B(...);

B.SetValueFromPoiner(&A); // &A => (return &A.value).

How to write this operator ?

You can't overload the '&' operator. I would suggest overloading the
'SetValueFromPointer' function so that it accepts a pointer to
'CInteger'.

Hope this helps,
-shez-

[Pete Becker]

Marchello wrote:

class CInteger
{
public:
....
void SetValueFromPoiner(int *new_value)
{
value = *new_value;
}
....
private:
int value;
};

This class need an operator of getting address of 'value'.
Some like this:

CInteger A(...);
CInteger B(...);

B.SetValueFromPoiner(&A); // &A => (return &A.value).

How to write this operator ?

You can write it as a global operator:

int *operator&(const CInteger& obj) { return &obj.value; }

or as a member:

class CInteger
{
public:
// ...
int *operator&() const { return &value; }
};

But this usually leads to problems, because once you've done it you
can't easily take the address of a CInteger object.

--

Pete Becker
Dinkumware, Ltd. (http://www.dinkumware.com)

[Phil Endecott]

Rapscallion wrote:

Phil Endecott wrote:

You cannot overload operator&. It is one of a very few operators that
cannot be overloaded.

Unfortunately you can. But you shoudn't!

I stand corrected. FAQ section 13.5.

I can imagine that very many things will stop working properly if you
do, though.

Marchello, why do you want to do this? What you are describing can be
achieved by writing B=A.

--Phil.

[Marchello]

> class CInteger

{
public:
// ...
int *operator&() const { return &value; }
};
Thanks, it's really work, but without 'const' (can't convert 'const int*' to
'int*').
But this usually leads to problems, because once you've done it you
can't easily take the address of a CInteger object.

Yes, I know. But it's just a little homework (I'm a student).

[Pete Becker]

Marchello wrote:

class CInteger
{
public:
// ...
int *operator&() const { return &value; }
};

Thanks, it's really work, but without 'const' (can't convert 'const int*' to
'int*').

Whoops... But you probably also need a non-const version.

--

Pete Becker
Dinkumware, Ltd. (http://www.dinkumware.com)

[Samee Zahur]

> You can write it as a global operator:

or as a member:
But this usually leads to problems, because once you've done it you
can't easily take the address of a CInteger object.

Question:
If operator& is defined as a member function, how do I take the address
of that object? The only way I can think of is with a wrapper class ...
but does it really become that difficult?

Samee

[Pete Becker]

Samee Zahur wrote:

You can write it as a global operator:
or as a member:
But this usually leads to problems, because once you've done it you
can't easily take the address of a CInteger object.

Question:
If operator& is defined as a member function, how do I take the address
of that object?

Try it.

--

Pete Becker
Dinkumware, Ltd. (http://www.dinkumware.com)