On 25 Dec 2005 22:15:51 -0800, "meendar"
<askjavaprogrammers@gmail.com> wrote:
[color=blue]
>what will a object of an Empty class( contain nothing), do on
>default.What are all the default methods it calls. what is the use of
>creating the object for an empty class?[/color]
C++ has no "methods", only functions and member functions.
What do you mean by empty? No data members? No member functions?
An object by itself does not call any functions. Your program calls
the functions. The constructor (or one constructor out of several if
there are more than one) is called when the object is created, and the
destructor is called when it is destroyed. But your program is
responsible for creation and deletion, so here it is also your program
that calls these, at least indirectly.
Consider the following:
struct Empty {};
I suppose that is as close as one can come to an empty class. However,
the C++ standard requires stand-alone objects of such empty classes to
have non-zero size (see section 9.2). If Empty is used as a base
class, the compiler is allowed to optimize its size away to zero bytes
within the derived class. Since we declared no default constructor,
destructor or assignment operator, the compiler generates these for
us. You can create objects of this class. Such empty classes are often
used in exception handling where the type is the only thing of
interest.
--
Bob Hairgrove
NoSpamPlease@Home.com 
