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  1. stackoverflow.com

    The Derived class destructor reset the vptr points to the Base class vtable, which has the pure virtual function, so when we call the virtual function, it actually calls into the pure virutal ones. This could happen because of an obvious code bug, or a complicated scenario of race condition in multi-threading environments.
  2. geeksforgeeks.org

    Jan 11, 2025Learn how to declare and use pure virtual functions and abstract classes in C++, which are classes that cannot be instantiated and require overriding of some functions in derived classes. See examples, comparison with Java, and interface vs abstract class concepts.
  3. learn.microsoft.com

    Learn how to fix this error caused by calling a virtual function in an abstract base class through a pointer to the base class. See the common reasons, steps to repair or reinstall the program, and information for programmers.
  4. geeksforgeeks.org

    Jan 16, 2025Learn the difference between virtual and pure virtual functions in C++, which are concepts of runtime polymorphism. A virtual function can be redefined by a derived class, while a pure virtual function must be defined by a derived class.
  5. stackoverflow.com

    Here are a few cases in which a pure virtual call can happen. Using a dangling pointer - the pointer isn't of a valid object so the virtual table it points to is just random memory which may contain NULL; Bad cast using a static_cast to the wrong type (or C-style cast) can also cause the object you point to to not have the correct methods in its virtual table (in this case at least it really ...
  6. answers.microsoft.com

    Hello everyone, Usually I can troubleshoot problems myself, but since I am here this means this problem has me completely stumped. EVERY SINGLE web browser that I have tried produces the following
  7. A pure virtual function is a function that must be overridden in a derived class and need not be defined. ... The time-cost overhead is also fairly nominal: compared to a normal function call, a virtual function call requires two extra fetches (one to get the value of the v-pointer, ...
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  1. They can result if you try to make a virtual function call from a constructor or destructor. Since you can't make a virtual function call from a constructor or destructor (the derived class object hasn't been constructed or has already been destroyed), it calls the base class version, which in the case of a pure virtual function, doesn't exist.

    class Base
    {
    public:
        Base() { reallyDoIt(); }
        void reallyDoIt() { doIt(); } // DON'T DO THIS
        virtual void doIt() = 0;
    };
    
    class Derived : public Base
    {
        void doIt() {}
    };
    
    int main(void)
    {
        Derived d;  // This will cause "pure virtual function call" error
    }

    See also Raymond Chen's 2 articles on the subject

    --Adam Rosenfield

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