What is abstract data type in c plus plus?

Answer 1

Abstract data types are the opposite of a concrete data types. An abstract data type is one that does not contain all of the function code necessary to create an instance of the object. This design allows subclasses to implement the abstract functions while inheriting the non-abstract functions of the class. A pointer to an abstract instance can call all the abstract functions of that object, which will defer their execution to the actual concrete data type's implementation of that function. As a simple example, an abstract class ChessPiece might have a function called move(). A Pawn subclass would behave differently than a Queen would, but both could be called by outside code without knowing (or caring) about what type of ChessPiece is moving.

Correction

Abstract classes can provide a full and complete (if generic) implementation for all of their pure-virtual functions. It is not the lack of a complete implementation that renders them abstract, but the fact the methods were declared pure-virtual and therefore cannot be inherited. However, derived classes can still call those implementations from within their own implementations.

Furthermore, derived classes that do not provide implementations for all the pure-virtual methods become abstract base classes themselves. But the pure-virtual methods that they do implement can then be inherited through multi-level inheritance.

Non-inheritance of pure-virtual methods only applies to the class that initially declared the method as pure-virtual. Provided an implementation is declared protected or public within a derived class, that implementation can then be inherited by a concrete class, or it can be overridden if required.

Answer 2

In C++, an abstract data type is a class that must be derived into a child class. It is not possible to instantiate an abstract class. Another way to define this is to say that an abstract class contains pure virtual functions or that it inherits from a class with pure virtual functions but does not provide an implementation for them.

Answer 3

An abstract data type is an abstract base class, a class which declares one or more pure-virtual methods. You cannot instantiate an abstract base class other than by deriving an object from the class. The derivative must provide the implementation for the pure-virtual methods it inherits otherwise it also becomes and abstract data type. Once an implementation is provided, the method reverts to a virtual function, which can then be inherited by more specific derivatives. However, only derivatives that provide or inherit a complete implementation can actually be instantiated. The purpose of an abstract data type is to provide a common interface to all its derivatives, much like a standard base class, but where the class is conceptual rather than actual. For instance, a shape is a conceptual class whereas circles and squares are actual classes.

Data abstraction is often confused with data hiding, however data abstraction simply refers to the way in which it is not necessary to know the internal details of an object in order to use an object. Nothing is actually hidden, it's just that there's no need to know. Data hiding is actually a function of binary libraries and other executables where information is obfuscated by the machine code.

Answer 4

If you mean basic data types as in intrinsic types (such as char, int, bool, short, long, etc) then no, they are not abstract. They are primitives.

Standard template library (STL) types such as list, queue, vector, etc, are abstract data types since they can be constructed from any existing type (primitive or user-defined, including other abstract types) in order to provide a container for that type.

Answer 5

An abstract data type (ADT) is a class that has one or more pure-virtual functions. Even if the ADT provides a default implementation for its pure-virtual methods, you cannot instantiate an object from an ADT, you must derive a class from it and provide a specific implementation. If a derived class does not fully implement the pure-virtual functions, it becomes an ADT itself, but subsequent derivatives can inherit any implementations it does provide.

An ADT is a conceptual object rathar than an actual object, and is intended to provide a common interface to all of its derivatives. Calling a pure-virtual method implicitly upon an ADT will invoke the most-derived class method, thus ensuring the expected behaviour of the derivative via the common interface.

An ADT is also known as an abstract base class (ABC).

An example of an ADT is a shape class. A shape class may have size (a bounding rectangle) and a position member, as well as a draw method, but a shape cannot draw itself because a shape is conceptual. Circles and squares are actual shapes, so they can both inherit from the shape class and implement the Draw() method accordingly. And since all shapes have a common ADT, collections of different shapes can be created, regardless of their actual type. Calling the Draw() method on any ADT in the collection will invoke the Draw() method in the square or circle, whichever is appropriate for that particular shape. That is, the caller doesn't need to know what the actual shape is, it only needs to know that every shape has a Draw() method -- the fact it is a pure-virtual method is immaterial to the caller. As far as the caller is concerned, it has a collection of shape ADTs and every shape has the ability to draw itself.

Answer 6

An abstract data type is any class or struct that contains at least one pure virtual function.

Answer 7

No. Abstract datatypes in C++ are classes which declare one or more pure-virtual functions. Basic datatypes are primitives and are therefore not classes, and thus are not abstract datatypes.

Answer 8

Yes, C++ has data types.