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What is the difference between Virtual Base Class and Abstract Class in c plus plus?
Wiki User
∙ 11y ago
You might as well compare apples and Oranges. The only thing they have in common is that they are both base classes (just as apples and oranges are both fruit).
An abstract base class is an abstract data type (ADT). An ADT is defined as any class that declares one or more pure virtual functions. This prevents anyone from instantiating objects from the class other than through derivation. The derivative must implement all pure-virtual methods declared in its base class, otherwise it becomes an ADT itself. Once a derivative overrides a pure-virtual method, that method becomes virtual with respect to all subsequent derivatives. However, only derivatives that provide or inherit a complete implementation for the sum of all pure-virtual methods can physically be instantiated.
A virtual base class is a base class that is inherited virtually. That is, if class A is declared a virtual base class of class B, then any derivative of B will automatically inherit directly from A. This is useful in multiple inheritance where two or more intermediate classes are themselves derived from a common base class. Normally, the most-derived class will inherit one instance of the common base class from each of the intermediate base classes. By declaring the common base class to be virtual in the intermediate classes, the most-derived class inherits just one instance of the common base class, which is then shared amongst the intermediate classes.
Thus if class A inherits from classes B and C and they each inherit from D, then there will be two instances of D in the hierarchy (A::B::D and A::C::D). This introduces ambiguity when referring directly to A::D. But if B and C inherit from D virtually, then there is only one instance of D (A::D), and both B and C derive from this one, shared instance, virtually. This removes any ambiguity and reduces the overall footprint of the hierarchy by eliminating redundant instances of the shared base class.
Ideally, virtual base classes should have little or no data members.
Wiki User
∙ 10y ago
Wiki User
∙ 11y agoabstract class no defination used by derieved class where virtual base class is defination that can be overriden later on
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Is an abstract class virtual by default?
Unlike abstract class in C++, the abstract class in C# does not have any methods defined as virtual by default. The concept of virtual are not the same between C# and C++, either. Any virtual method must be defined explicitly in C#. Related to abstract methods - interestingly, an abstract class in C# does not have to have any abstract methods. However, the reverse, if a class need to have at least one abstract method, that class must be defined as abstract.
Write abstract class in c plus plus?
An abstract class is any class definition that contains at least one pure-virtual function. class AbstractClass { public: virtual void DoSomething()=0; // Pure-virtual. };
What is the difference between abstract class and normal class?
Any class which has one or more abstract methods is called an abstract class. But in the normal class we can't have any abstract methods. We cannot create an object for the abstract classes. When we inherit the abstract class we should implement the abstract method which we inherit.
What is the difference between association class and abstract class in software designing?
Association class is describing the relationship between classes. An abstract class is just 1 class, provides some abstraction behaviors that may be (but do not have to) derived, overridden from.
What is an abstract class Write the syntax Declare a pure virtual function in an abstract class?
an abstract class is nothing but class which contains both abstract and concrete methods for abstract class we r nt create object Syntax for pure abstract class is abstract class x { public void abstract y(); public void abstract z(); public void abc() { }
Is an abstract class virtual by default?
Unlike abstract class in C++, the abstract class in C# does not have any methods defined as virtual by default. The concept of virtual are not the same between C# and C++, either. Any virtual method must be defined explicitly in C#. Related to abstract methods - interestingly, an abstract class in C# does not have to have any abstract methods. However, the reverse, if a class need to have at least one abstract method, that class must be defined as abstract.
What is the difference between abstract class and final class?
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What is the difference between abstarct class and virctulfunction in C sharp?
They are not comparable, but may have some relationship between them.An abstract class is a class, while a virtual function (or method) is a method. A method must exist within a class. Hence, a class has methods, and the methods may be defined as virtual functions.A virtual function must be defined in a class, but that class does not have to be an abstract class. However, the purpose of a virtual function in C# is to provide a default behavior/implementation, while allowing the derived class to override that default implementation, hence it makes no sense to define a virtual function in a sealed class (a leaf, that is, no class can extend from it, and it is not an abstract class)Example:public class Parent {public virtual string MostCommonPhrase() {return "You better listen to me...";}}public class Child : Parent {public override string MostCommonPhrase() {return "You never listen to me...";}}
Write abstract class in c plus plus?
An abstract class is any class definition that contains at least one pure-virtual function. class AbstractClass { public: virtual void DoSomething()=0; // Pure-virtual. };
What is the difference between abstract class and normal class?
Any class which has one or more abstract methods is called an abstract class. But in the normal class we can't have any abstract methods. We cannot create an object for the abstract classes. When we inherit the abstract class we should implement the abstract method which we inherit.
What is the difference between association class and abstract class in software designing?
Association class is describing the relationship between classes. An abstract class is just 1 class, provides some abstraction behaviors that may be (but do not have to) derived, overridden from.
What is abrstac class and virctulfunction in c sharp?
abstract class is a class label with abstract. It is just like a common class, with the following characterics: 1. Abstract class cannot be instantiate with an instance. 2. Abstract class may have abstract methods, while the normal class cannot have abstract methods. a virtual function in C# is a way to provide a default implementation for the class hierarchy. Both abstract class and common class (not sealed) can have virtual methods/ functions. Note that an abstract method (of an abstract class) is defining the intent, no codes (no default behavior), the implementation are left for the derived classes to do so. The virtual function if defined in an abstract class must define the implementation, the minimum is to do nothing: public abstract class Vehicle { public abstract int GetNumberOfTires(); public virtual void Move() { // default is doing nothing} } public class Car : Vehicle { public override int GetNumberOfTires() { return 4; } public override void Move() { throws new OutOfFuelExpection(); } }
What is an abstract class Write the syntax Declare a pure virtual function in an abstract class?
an abstract class is nothing but class which contains both abstract and concrete methods for abstract class we r nt create object Syntax for pure abstract class is abstract class x { public void abstract y(); public void abstract z(); public void abc() { }
How do you write concrete method inside abstract class?
There is no difference with method declaration and implementation between abstract and non-abstract classes. You do the exact same thing when writing a concrete method in either an abstract or non-abstract class.
Difference between abstract and final class?
Abstract class is built to promote inheritance whereas a final class is built to avoid inheritanceAn Abstract class can be extended by another class whereas a final class cannot be extended
What is difference between interface and abstract class?
All the methods declared inside an Interface are abstract. Where as abstract class must have at least one abstract method and others may be concrete or abstract. In Interface we need not use the keyword abstract for the methods.
What is the major difference between an Interface and a Class?
An interface can only have abstract methods or constants in it. A class can have both that and everything else in Java.
