What is vtable

Remember that when these virtual tables are filled out, each entry is filled out with the most-derived function an object of that class type can call. The virtual table for Base objects is simple. An object of type Base can only access the members of Base. Base has no access to D1 or D2 functions. Consequently, the entry for function1 points to Base::function1 and the entry for function2 points to Base::function2. The virtual table for D1 is slightly more complex.

An object of type D1 can access members of both D1 and Base. However, D1 has overridden function1 , making Dfunction1 more derived than Base::function1. Consequently, the entry for function1 points to Dfunction1. The virtual table for D2 is similar to D1, except the entry for function1 points to Base::function1 , and the entry for function2 points to Dfunction2.

The entries in the virtual table point to the most-derived version of the function objects of that class are allowed to call. Note that because dPtr is a base pointer, it only points to the Base portion of d1.

Thanks for the article. Just a missing word: In Every object first 4 bytes will BE a pointer that points to the vTable of that class. Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed. How virtual functions works internally using vTable and vPointer? Varun February 19, How virtual functions works internally using vTable and vPointer? For example, When we make a function call like, obj. Dynamic Binding or Run Time Binding: When we make a member function virtual then compiler performs run time binding for that function i. Create a Derived class from MessageCoverter i.

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