Have some knowledge about polymorphism--you deserve it.

Polymorphism, as the name implies, is a variety of forms. It's like everyone makes a different choice about everything.

The first point of order for polymorphism to be expressed here is the application of the Richter scale substitution and polymorphism:

The Richter replacement is one of the important principles that should be adhered to in software design!! It is possible to inherit multiplexing with the Richter substitution rule, and the functionality of the software is not affected when the subclass replaces the parent class, the parent class is used normally, and the subclass can add new behavior on the basis of the parent class.

Let's write an example below:

 //  parent bird  public  class   bird{ //  Flight speed  public  double  Speed{get ; set                //  fly   void   Fly () {}}  //  ostrich  public  class   tuobird:bird{...  

But we all know that ostriches are not flying, where the Fiy () method does nothing. This goes against the Richter scale replacement.

In order to solve this problem, there are two operators: IS and as

Is operator: used to check whether the object and the specified type are compatible

As operator: For type conversions between two objects

Parent class as parameter: The Richter substitution principle indicates that the subclass object can be substituted for the parent class object, then in the development program you can write a method with the parent class type as the formal parameter, and pass the subclass object in the actual call to achieve polymorphism.

Let's write an example below:

 //  transport parent   class       Traffic  { // run  public  virtual  void   Run () {Console.WriteLine (   parent class Run        ); }    }

 //  car   class       Car:traffic  { public  override  void   Run () {Console.WriteLine ( "    "        ); }    }

 //  bike   class       Bicycle:traffic  { public  override  void   Run () {Console.WriteLine ( "   Xiaoming rode a very broken, broken-down, Phoenix-brand bike on March 1, 2016, happily driving in a muddy nim bumpy dirt road  
    
      "
     ); }    }

// Employee Class    Public class Employee    {         // go home       with     trafficpublic       void  gohome ( Traffic traffic)       {           traffic. Run ();       }    }

Abstract classes and abstract methods

How do you turn a normal class into an abstract class?

(1) Keywords: abstract

(2) Abstract classes cannot be instantiated

(3) The abstract method has no method body even {}

(4) If a class inherits an abstract class, then it must override all abstract methods in the abstract class.

(5) An abstract class cannot be static or sealed, such as a string

(6) Abstract methods exist in abstract class, abstract class can be used by ordinary class

(7) Abstract methods are only used to specify the method form of a subclass (parameter return value)

(8) Tell everyone the secret of the General people I do not say, there are shortcut keys ctrl+.+ enter

Let's talk about the difference between a virtual method and an abstract method.

Virtual method	Abstract methods
Modify with Virtual	To modify with an abstract
To have a method body even a semicolon	Method body is not allowed
You can override the quilt class	You must override the quilt class
can be defined except for sealed classes	can only be defined in abstract classes

Have some knowledge about polymorphism--you deserve it.