Why Do We Use Abstract Class In Cpp

Therefore we have an abstract method in abstract base class.

Why do we use abstract class in cpp. Classes inheriting an abstract class must provide definition to the pure virtual function otherwise they will also become abstract class. Abstract class is a class which contains atleast one pure virtual function in it. Abstract classes act as expressions of general concepts from which more specific classes can be derived. For example let shape be a base class.

The purpose of an abstract class often referred to as an abc is to provide an appropriate base class from which other classes can inherit. However you can use pointers and references to abstract class types. Why we need a abstract class. Sometimes implementation of all function cannot be provided in a base class because we dont know the implementation.

No objects of an abstract class can be created except for base subobjects of a class derived from it and no non static data members of an abstract class can be declared. Attempting to instantiate an object of an abstract class causes a compilation error. C abstract class is conceptually a class that cannot be instantiated and it should be implemented as a class that has one or more pure virtual abstract functions. A pure virtual function is marked with a virtual keyword and has 0 after its signature.

Pure virtual functions and abstract classes in c. A pure virtual function is one which must be overridden by any concrete ie non abstract derived class. The purpose of an abstract class is to define a common protocol for a set of concrete subclasses. This is useful when defining objects that share code abstract ideas etc.

Abstract classes are used to provide an interface for its sub classes. Such a class is called abstract class. You can call this function an abstract function as it has no body. First any class with one or more pure virtual functions becomes an abstract base class which means that it can not be instantiated.

The creation of connection is specific to the derived class. An abstract class must have at least one deferred method or function. Abstract classes are used to represent general concepts for example shape animal which can be used as base classes for concrete classes for example circle dog. Abstract classes cannot be used to instantiate objects and serves only as an interface.

The derived class must give the implementation to all the pure virtual functions of parent class else it will become abstract class by default. When we add a pure virtual function to our class we are effectively saying it is up to the derived classes to implement this function. Abstract class and pure virtual function in c. Though it is a very basic and small example but it can help you to understand the use of an abstract class.

We cannot provide implementation of function draw in shape but we know every derived class must have implementation of draw. A class that contains at least one pure virtual function is considered an abstract class.