Override and virtual of classes in C ＃

Welcome to be my reader , I hope this article can give you some help .

Preface

I learned class derivation with you yesterday , Know the difference between derived class and base class .

Today, let's look at how the virtual methods and override methods of derived classes and base classes are used .

When we use base class references to access derived class objects , You get members of the base class . When using virtual methods , You can get the members and functions of the derived class .

 class Ahui:InfoBase
 {
     public string Name = " aunt ";
          
     public string GetInfo() 
     {
         return this.Name+""+this.Age;
     }
 
 class InfoBase 
 {
     public int Age=27;
     public string Name = "ahui" 
     public string GetInfo() 
     {
         return Name;
      
     public string Love() 
     {
         return " Woman ";
     }
 }

The above code is a simple expression of base and derived classes , We try to pass the base class InfoBase To access derived classes Ahui The methods inside are shown in the output above .

 static void Main(string[] args)
 {
     Ahui hui = new Ahui();
     InfoBase info = (InfoBase)h
     Console.WriteLine(hui.GetInfo());
     Console.WriteLine(info.GetInfo());
     Console.ReadKey();
  }

From the above picture, you can see the access to... Through their respective instances GetInfo() Method returns different values , The base class returns its own , The derived class returns its own .

So when we want to use the reference of the base class to access the derived class object , Virtual methods can be used to access .

It must meet the following conditions ：

• The method of the derived class and the method of the base class have the same signature and return type .
• The methods of the base class use virtual mark .
• Methods of derived classes use override mark .

 class Ahui:InfoBase
 {
     public string Name = " aunt ";
          
     public override string GetInfo() 
     {
         return this.Name+""+this.Age;
     }
     
 class InfoBase 
 {
     public int Age=27;
     public string Name = "ahui"     public virtual string GetInfo() 
     {
         return Name;
          public string Love() 
     {
         return " Woman ";
     }
 }

Compare with the last output picture , You can see that when using virtual methods and overriding tags , All the output are members of derived classes .

It should be noted that ：

• Overridden and overridden methods must have the same accessibility .
• Cannot override static Method or non virtual method .
• Method 、 Properties and indexers 、 Member type events can be declared as virtual and override.

remarks

Life is short , I don't want to pursue what I can't see , I just want to catch what I can see .

Originality is not easy. , Pay attention .

I am a A Hui , Thank you for reading , If it helps you , Please like it 、 forward thank you .

I'm glad to be friends with you .