Hi

In the Adobe Indesign development I have e.g. the following declaration in
the header file of an interface:

virtual int test(int i) = 0;

Whats the "= 0" at the end of the declaration? I mean in a normal header
file in C++ I can't do that.

Thanks for the information.

Regards
Hans

* Hans Stoessel:[color=blue]
>
> In the Adobe Indesign development I have e.g. the following declaration in
> the header file of an interface:
>
> virtual int test(int i) = 0;
>
> Whats the "= 0" at the end of the declaration?[/color]

It means that an a definition must be / is provided in a derived class.

Also that the class containing the "= 0" can not be instantiated.

A member function designated with "= 0" is called a pure virtual member
function, and a class containing a pure virtual member, an abstract class.

[color=blue]
> I mean in a normal header file in C++ I can't do that.[/color]

You can.

--
A: Because it messes up the order in which people normally read text.
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> Hi[color=blue]
>
> In the Adobe Indesign development I have e.g. the following declaration in
> the header file of an interface:
>
> virtual int test(int i) = 0;
>
> Whats the "= 0" at the end of the declaration?[/color]

It means that the function is pure virtual and the class that contains
this function is an abstract class. You cannot create instances of
abstract classes. The class inheriting from such a class must provide
an implementation for the pure virtual function.
[color=blue]
> I mean in a normal header file in C++ I can't do that.
>[/color]

Huh?? What do you mean by "normal header file in C++"?? You cannot
declare pure virtual functions outside classes. In other words, a
function cannot be pure virtual unless its a member function of some
class.
[color=blue]
> Thanks for the information.
>
> Regards
> Hans[/color]

Srini