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How dynamic binding acheived in c plus plus?
Dynamic binding is achieved via virtual functions and the virtual table that is associated with every class that declares or inherits a virtual function. The virtual table (or v-table) maps every virtual function (including pure-virtual functions) to a function pointer that points to the most-derived overload. This makes it possible to invoke specific behaviour even when the runtime type of the object is unknown to the caller.
A pure virtual function is a virtual function that has?
A pure-virtual function is a function that must be overridden in derived classes. You simply add "=0" to the end of the function declaration. class AbstractClass { public: virtual void DoSomething()=0; // Pure-virtual. };
What virtual table in a database is known as a?
A view table.
What is virtual function in c plus plus?
A virtual function is a member function of a class, whose functionality can be over-ridden in its derived classes. It is one that is declared as virtual in the base class using the virtual keyword. The virtual nature is inherited in the subsequent derived classes and the virtual keyword need not be re-stated there. The whole function body can be replaced with a new set of implementation in the derived class
Rules of virtual function?
AnswerA virtual function must be declared as a non-static member method of a class that you expect to act as a base class. Declaring a virtual function adds some overhead as a result of creating the v-table (virtual method table), but most of that overhead is paid with the first virtual function (subsequent virtual functions just add a new entry to the already-existing v-table). However, do not declare a virtual function unless you expect that function to be overridden. Bear in mind that overriding an overloaded, non-virtual function "hides" all the overloads in the base class.If a virtual function must be overridden, declare it as pure-virtual instead. You do not need to implement the method in the base class, but you will be reminded to provide an implementation in the derived class at compile time if one does not exist, even if you provide a default implementation in the base class. Bear in mind that base classes with one or more pure-virtual methods become abstract -- they cannot be instantiated.If there is any virtual function or pure-virtual function, there must also be a virtual destructor, as well as a public or protected default constructor (a constructor with no arguments). When a derived class is constructed, it calls the base class constructor, which calls its base class constructor. Derived classes are constructed in sequence, beginning with the least-derived class. Destruction is the reverse -- the most-derived class is destroyed before the base classes are destroyed.Virtual functions can be invoked just like any other class member method, both via an object reference's member operator (.), and the indirection operator (-->) for pointers to objects. It does not matter whether the reference or pointer refers to a base class or a derived class; the v-table decides which override (where one is provided) will actually execute, starting from the most-derived override and working back towards the base class, the least-derived. With appropriate use of virtual functions, dynamic casting can be avoided completely (dynamic casting should never be employed as it completely defeats the point of having a v-table in the first place).Answer1.the virtual function should be a member of some class 2.they cannot be a static member 3.they are accessed by using object pointers
What is the difference between virtual function and function overriding?
Virtual Functions and Pure Virtual Functions are relevant in the context of class inheritance.Unlike Virtual Functions, Pure Virtual Functions do not require a body. This implies that when a base class defining such a function is inherited, the derived class must implement that function. Furthermore, the base class becomes abstract; meaning you cannot create an instance of the base class even if a body is implemented for the function. You are expected to derive from abstract classes; only the derived classes that implement all the inherited Pure Virtual functions can be instantiated.Here are some examples of Virtual and Pure Virtual function signatures:- Virtual Function: E.g. virtual void myFunction();- Pure Virtual Function: E.g. virtual void myFunction() = 0;
What is a function table?
a function table is a table used to find number pairs
Can you have inline virtual functions in a class?
No, inlining is done at compile time whereas virtual functions are resolved at run time(late binding). So, virtual functions can't be inlined. Both properties are orthogonal.Inlining is a mere suggestion the compiler may ignore it if it is declared with virtual function.
Which binding virtual function used?
Virtual functions are dynamically bound at runtime.
Can a static function be made virtual?
No. Virtual functions are invoked according to the runtime type of the object. That is; the most-derived override is automatically invoked even when the runtime type of the object cannot be determined at compile time. This is achieved through the object's virtual table. Static methods do not have any object associated with them; they can be invoked even when no object of the type exists. Without an object, there can be no virtual table. Thus static functions cannot be virtual. They are mutually exclusive concepts.
What is the different between a view and a create view?
View is a virtual table that do not have any data of its own but have data that is derived from another table called base table. Create view is the command used to create a view (virtual table).
Application of object-oriented programming?
AnswerA virtual function must be declared as a non-static member method of a class that you expect to act as a base class. Declaring a virtual function adds some overhead as a result of creating the v-table (virtual method table), but most of that overhead is paid with the first virtual function (subsequent virtual functions just add a new entry to the already-existing v-table). However, do not declare a virtual function unless you expect that function to be overridden. Bear in mind that overriding an overloaded, non-virtual function "hides" all the overloads in the base class.If a virtual function must be overridden, declare it as pure-virtual instead. You do not need to implement the method in the base class, but you will be reminded to provide an implementation in the derived class at compile time if one does not exist, even if you provide a default implementation in the base class. Bear in mind that base classes with one or more pure-virtual methods become abstract -- they cannot be instantiated.If there is any virtual function or pure-virtual function, there must also be a virtual destructor, as well as a public or protected default constructor (a constructor with no arguments). When a derived class is constructed, it calls the base class constructor, which calls its base class constructor. Derived classes are constructed in sequence, beginning with the least-derived class. Destruction is the reverse -- the most-derived class is destroyed before the base classes are destroyed.Virtual functions can be invoked just like any other class member method, both via an object reference's member operator (.), and the indirection operator (-->) for pointers to objects. It does not matter whether the reference or pointer refers to a base class or a derived class; the v-table decides which override (where one is provided) will actually execute, starting from the most-derived override and working back towards the base class, the least-derived. With appropriate use of virtual functions, dynamic casting can be avoided completely (dynamic casting should never be employed as it completely defeats the point of having a v-table in the first place).
