"osmium" <r124c4u102@comcast.net> schrieb im Newsbeitrag
news:4923u1Fm41vjU1@individual.net...

"Ajay" writes:

i want to know when i create a class.what all it
contains.I
know the following things are there by default if i do not declare
them
by myself.Please tell the other things that are left.

1. constructor
2.Destructor
3.Copy constructor
4. Assignment operator

Your list is complete, there ain't no more. The implicit copy
constructor, especially, can really spoil your day if you are a
novice. Because a novice may not be aware that he is even invoking
the copy constructor, much less realize that the CC does not do what
he needs to have done. It might be nice to have a C++ compiler with
training wheels that emits the following message:

"Warning! You have implicitly called the copy constructor. You may
be sorry."

Even better: The standart should tell the default CC to use the
(default or not) = operator.

If you do not implement your own Destructor, a compiler maybe generates
one automatically or generates nothing,. BUT it does not generate one
does the wrong thing .

* Daniel T.:

In article <1143709690.868142.310590@u72g2000cwu.googlegroups.com>,
"Ajay" <ajay.kumarCS@gmail.com> wrote:

Hi all,
i want to know when i create a class.what all it contains.I
know the following things are there by default if i do not declare them
by myself.Please tell the other things that are left.

1. constructor
2.Destructor
3.Copy constructor
4. Assignment operator

Thanks in advance.

From Scott Meyers' book:

... if you write this:

class Empty { };

it's the same as if you'd written this:

class Empty {
public:
Empty() { }
Empty( const Empty& rhs );
~Empty() { }
Empty& operator=( const Empty& rhs );
Empty* operator&() { return this; }
const Empty* operator&() const { return this; }
};

Uhuh. Did Scott Meyer really write that?

Daniel T. wrote:

From Scott Meyers' book:

... if you write this:

class Empty { };

it's the same as if you'd written this:

class Empty {
public:
Empty() { }
Empty( const Empty& rhs );
~Empty() { }
Empty& operator=( const Empty& rhs );
Empty* operator&() { return this; }
const Empty* operator&() const { return this; }
};

Ah, but from the errata list for that book
(http://www.aristeia.com/BookErrata/ec++2e-errata_frames.html):

A class declaring no operator& function(s) does NOT have them
implicitly declared. Rather, compilers use the built-in address-of
operator whenever "&" is applied to an object of that type. This
behavior, in turn, is technically not an application of a global
operator& function. Rather, it is a use of a built-in operator.

I eliminated mention of operator& as an automatically generated
function and adjusted the index to eliminate entries for the removed
material.

This was fixed in September 2001. I apologize for getting it wrong in
the first place.

I can't help but remark that I encourage you to take a look at the
third edition of the book, which came out about a year ago. Not only
does it not contain errors such as this (*), it includes lots of new
information that I believe is essential for effective C++ programming,
e.g., using objects to manage resources, writing exception-safe code,
implementing traits classes, etc.

Scott