Pure virtual function in other compilers

[vibindia]

Hi class A { public: virtual void fun()=0 { cout<<"hai";//code inside in an pure virtual function } }; this works in VC++.(code inside an pure virtual function) Is the same thing work in other compilers of C++:confused:

VIBIN "Fool's run away,where angle's fear to tread"

[C Mahesh]

I have the following questions : 1.Which version of VC++ compiler did you use? 2.What is your understanding of pure virtual functions?

[vibindia]

the version is VC++6.0 My understanding of Virtual fuction It creates an V table, which provides run time ploymorphism, And an pure virtual function makes the calss an Abstract base class.

VIBIN "Fool's run away,where angle's fear to tread"

[C Mahesh]

Great, As for i am aware, the compiler should not allow it, and even if it allows what is the use of it when the class is abstract. P.S: I have checked with VC++7.0, it gives an error

[Cedric Moonen]

The error will only be displayed if you try to actually instantiate the class: A myInstance; // This will fail But VC6 is also a very old compiler and not fully compliant to the actual standard.

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Cédric Moonen Software developer
Charting control [v1.2]

[David Crow]

vibindia wrote:

Is the same thing work in other compilers of C++

That sounds like a try-it-and-see question.

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"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

[James R Twine]

I believe that it is completely valid.  Declaring a function as pure virtual does not mean that does not have an implementation, only that you have to provide one in a derived class.    This can (and has) been used to force developers to customize behavior for their derived classes, but still provide an implementation in the base class.    It should only give you an error if you try to directly instantiate an instance of that base class, or of a derived on that does not provide an implementation for the PV function.    Of course, I could be wrong here...    Peace!

-=- James
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