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What is a vtable and how does it work?
For every class that contains virtual functions, the compiler constructs a virtual table, a.k.a vtable. The vtable contains an entry for each virtual function accessible by the class and stores a pointer to its definition. Only the most specific function definition callable by the class is stored in the vtable.
How do virtual functions work?
Virtual functions ensure that the correct function is called for an object, regardless of the type of reference (or pointer) used for function call. Functions are declared with a virtual keyword in base class. The resolving of function call is done at Run-time.
What is vTable and vPointer?
vTable is a kind of function pointer array that contains the addresses all virtual functions of this class. Compiler builds this vTable at compile time. vPointer: This vPointer points to the vTable of that class. This vPointer will be used to find the actual function address from vTable at run rime.
Where is virtual function used?
A virtual function is a member function in the base class that we expect to redefine in derived classes. Basically, a virtual function is used in the base class in order to ensure that the function is overridden. This especially applies to cases where a pointer of base class points to an object of a derived class.
Can multiple inheritance have virtual function?
You can, however derive non-virtual from A in C and B, but then you have no diamond inheritance anymore. That is, each data-member in A appears twice in B and C because you have two A base-class sub-objects in an D object.
How does a virtual function work in vtable?
Once a function is declared virtual in a class then for all its derived classes that function will remain virtual. Therefore in above class NewMessageConverter even if we haven’t declared convert function virtual but it will be considered as virtual because in its base class this function is virtual.
What does the V table mean in Java?
The v-table consists of addresses to the virtual functions for classes that contain one or more virtual functions. The object of the class containing the virtual function contains a virtual pointer that points to the base address of the virtual table in memory.
How does the compiler find the vtable of a function?
Compiler builds this vTable at compile time. Now for every object of a class that has a vTable associated with it, contains a vPointer in first 4 bytes. This vPointer points to the vTable of that class. This vPointer will be used to find the actual function address from vTable at run rime.
Which is an example of binding in vtable?
Binding is a kind of mapping of a function call with the function’s definition i.e. function’s address. For example, while code execution, correct function should be called.