Difference between virtual and abstract methods

Question

Here is some code from MSDN      compile with   target library  public class D       public virtual void DoWork int i                   Original implementation           public abstract class E   D       public abstract override void DoWork int i      public class F   E       public override void DoWork int i                   New implementation            Can anyone explain the above code with respect to the differences between abstract and virtual methods

User · Answer

First of all you should know the difference between a virtual and abstract method  Abstract Method  Abstract Method resides in abstract class and it has no body  Abstract Method must be overridden in non-abstract child class   Virtual Method  Virtual Method can reside in abstract and non-abstract class  It is not necessary to override virtual method in derived but it can be  Virtual method must have body     can be overridden by  quot override keyword quot

User · Answer

Virtual methods have an implementation and provide the derived classes with the option of overriding it  Abstract methods do not provide an implementation and force the derived classes to override the method    So  abstract methods have no actual code in them  and subclasses HAVE TO override the method  Virtual methods can have code  which is usually a default implementation of something  and any subclasses CAN override the method using the override modifier and provide a custom implementation   public abstract class E       public abstract void AbstractMethod int i        public virtual void VirtualMethod int i                   Default implementation which can be overridden by subclasses           public class D   E       public override void AbstractMethod int i                   You HAVE to override this method           public override void VirtualMethod int i                   You are allowed to override this method

User · Answer

Abstract Method   If an abstract method is defined in a class  then the class should declare as an abstract class   An abstract method should contain only method definition  should not Contain the method body implementation   An abstract method must be over ride in the derived class    Virtual Method   Virtual methods can be over ride in the derived class but not mandatory  Virtual methods must have the method body implementation along with the definition   Example  public abstract class baseclass                       public abstract decimal getarea decimal Radius                public virtual decimal interestpermonth decimal amount                                return amount 12 100                             public virtual decimal totalamount decimal Amount decimal principleAmount                                return Amount   principleAmount                                   public class derivedclass baseclass                       public override decimal getarea decimal Radius                                return 2    22   7    Radius                             public override decimal interestpermonth decimal amount                                return amount   14   100

User · Answer

an abstract method must be call override in derived class other wise it will give compile-time error and in virtual you may or may not override it s depend if it s good enough use it   Example    abstract class twodshape       public abstract void area       no body in base class    class twodshape2   twodshape       public virtual double area                 Console WriteLine  AREA   may be or may not be override

[c#] Difference between virtual and abstract methods

Abstract Method

Virtual Method

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