Virtual/Overidden class methods

This is a discussion on Virtual/Overidden class methods within the C++ Programming forums, part of the General Programming Boards category; I've recently been reading about virtual and over-riding class methods, and wondered what the difference really is, and whether it ...

  1. #1
    Let's do some coding! Welshy's Avatar
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    Virtual/Overidden class methods

    I've recently been reading about virtual and over-riding class methods, and wondered what the difference really is, and whether it matters to use either.
    I know the virtual functions enable the function to do different things in different classes, but surely you can just over-ride the function and get the same effect?

    Dunno if it would be too much to ask for an example of where each would be appropriate, thanks!

  2. #2
    Toaster Zach L.'s Avatar
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    Code:
    #include <iostream>
    
    struct base
    {
       virtual void f() const { std::cout << "base::f()" << std::endl; }
       void g() const { std::cout << "base::g()" << std::endl; }
    };
    
    struct derived : public base
    {
       virtual void f() const { std::cout << "derived::f()" << std::endl; }
       void g() const { std::cout << "derived::g()" << std::endl; }
    };
    
    int main()
    {
       base foo;
       derived bar;
       
       foo.f();
       foo.g();
    
       bar.f();
       bar.g();
       
       base* ptr = &bar;
    
       ptr->f();
       ptr->g();
    }
    There most certainly is a difference.

    *edit*
    And here is a very relevant link: It's legal, but it ain't moral.

    Cheers
    Last edited by Zach L.; 08-21-2005 at 10:51 AM.
    The word rap as it applies to music is the result of a peculiar phonological rule which has stripped the word of its initial voiceless velar stop.

  3. #3
    Let's do some coding! Welshy's Avatar
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    alright, thanks. Oh and cheers for the link, should minimise the need to post om here asking about inheritance again, hehe

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