"Learning notes" C # virtual method (virtual function)

• Method substitution
  • After the subclass inherits the parent class, you can hide the method in the parent class and re-implement it in the subclass
• Virtual functions and overrides
  • The method of virtual modification is called the virtual method, and the override method is called rewriting.
  • Only methods and properties can be virtual, fields cannot be virtual
• The difference between abstract and virtual methods
  • 1. The abstract method must be in an abstract class, and the virtual method may not.
  • 2. Abstract methods cannot be implemented in a parent class, and virtual methods can not.
  • 3. Abstract methods must be implemented in non-abstract subclasses, and virtual methods can not
• Polymorphic--Uses the parent class type to invoke the method implemented in the subclass

• 1 usingSystem;2 3 namespaceVirtualmethoddemo4 {5      Public classSuper6     {7          Public Virtual stringName8         {9             GetTen             { One                 return "Li"; A             } -         } -  the          Public voidA () -         { -Console.WriteLine ("This method is defined in Super in a! "); -         } +         //virtual Method -  +         //the difference between abstract and virtual methods A         //1. The abstract method must be in an abstract class, and the virtual method may not.  at         //2. Abstract methods cannot be implemented in a parent class, and virtual methods can not.  -         //3. Abstract methods must be implemented in non-abstract subclasses, and virtual methods can not -          Public Virtual voidB () -         { -Console.WriteLine ("This method is the B defined in Super! "); -         } in     } -  to      Public classSub:super +     { -  the          Public Override stringName *         { $             GetPanax Notoginseng             { -                 return "Zhao"; the             } +         } A         //method Substitution-Re-implementing the method defined in the parent class in the subclass the          Public New voidA () +         { -Console.WriteLine ("This method is defined in Sub in a! "); $         } $  -         //virtual Method -         //This method can not be written.  the          Public Override voidB () -         {WuyiConsole.WriteLine ("This method is the B defined in Sub! "); the         } -     } Wu     class Program -     { About         Static voidMain (string[] args) $         { -             //referencing the parent class object using the parent class type -Super Super =NewSuper (); -Super. A ();//called a method defined in the parent class ASuper. B ();//called a method defined in the parent class + Console.WriteLine (Super. Name); the  -             //referencing child class objects using subclass Types $Sub Sub =NewSub (); theSub. A ();//called a method defined in a subclass theSub. B ();//called a method defined in a subclass the Console.WriteLine (Sub. Name); the  -             //referencing a subclass object using the parent class type inSuper C =NewSub (); theC.A ();//called a method defined in the parent class theC.B ();//called a method defined in a subclass About Console.WriteLine (c.name); the  the             //polymorphic--Uses the parent class type to invoke the method implemented in the subclass the         } +     } -}

"Learning notes" C # virtual method (virtual function)