C# 声明公共类别A:B是什么意思

这也许是个愚蠢的问题，但宣布这一点意味着什么：

public class A: B{


}

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我理解继承，我只是开始使用C#语法。这意味着A类继承自B类。web上有很多关于继承的资料。

这表示该类继承自B类，或实现接口B。

这可能意味着两件事：

• 您是从类继承的
• 您正在实现一个接口

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这是面向对象编程的一个基本概念，因此在internet上查找信息应该不会有任何问题。

您应该阅读本文

它意味着两件事

• 您是从类继承的
• 您正在实现一个接口

看看这段代码，你就会明白了

// WorkItem implicitly inherits from the Object class.
public class WorkItem
{
    // Static field currentID stores the job ID of the last WorkItem that
    // has been created.
    private static int currentID;

    //Properties.
    protected int ID { get; set; }
    protected string Title { get; set; }
    protected string Description { get; set; }
    protected TimeSpan jobLength { get; set; }

    // Default constructor. If a derived class does not invoke a base-
    // class constructor explicitly, the default constructor is called
    // implicitly. 
    public WorkItem()
    {
        ID = 0;
        Title = "Default title";
        Description = "Default description.";
        jobLength = new TimeSpan();
    }

    // Instance constructor that has three parameters.
    public WorkItem(string title, string desc, TimeSpan joblen)
    {
        this.ID = GetNextID();
        this.Title = title;
        this.Description = desc;
        this.jobLength = joblen;
    }

    // Static constructor to initialize the static member, currentID. This
    // constructor is called one time, automatically, before any instance
    // of WorkItem or ChangeRequest is created, or currentID is referenced.
    static WorkItem()
    {
        currentID = 0;
    }


    protected int GetNextID()
    {
        // currentID is a static field. It is incremented each time a new
        // instance of WorkItem is created.
        return ++currentID;
    }

    // Method Update enables you to update the title and job length of an
    // existing WorkItem object.
    public void Update(string title, TimeSpan joblen)
    {
        this.Title = title;
        this.jobLength = joblen;
    }

    // Virtual method override of the ToString method that is inherited
    // from System.Object.
    public override string ToString()
    {
        return String.Format("{0} - {1}", this.ID, this.Title);
    }
}

// ChangeRequest derives from WorkItem and adds a property (originalItemID) 
// and two constructors.
public class ChangeRequest : WorkItem
{
    protected int originalItemID { get; set; }

    // Constructors. Because neither constructor calls a base-class 
    // constructor explicitly, the default constructor in the base class
    // is called implicitly. The base class must contain a default 
    // constructor.

    // Default constructor for the derived class.
    public ChangeRequest() { }

    // Instance constructor that has four parameters.
    public ChangeRequest(string title, string desc, TimeSpan jobLen,
                         int originalID)
    {
        // The following properties and the GetNexID method are inherited 
        // from WorkItem.
        this.ID = GetNextID();
        this.Title = title;
        this.Description = desc;
        this.jobLength = jobLen;

        // Property originalItemId is a member of ChangeRequest, but not 
        // of WorkItem.
        this.originalItemID = originalID;
    }
}

class Program
{
    static void Main()
    {
        // Create an instance of WorkItem by using the constructor in the 
        // base class that takes three arguments.
        WorkItem item = new WorkItem("Fix Bugs",
                                     "Fix all bugs in my code branch",
                                     new TimeSpan(3, 4, 0, 0));

        // Create an instance of ChangeRequest by using the constructor in
        // the derived class that takes four arguments.
        ChangeRequest change = new ChangeRequest("Change Base Class Design",
                                                 "Add members to the class",
                                                 new TimeSpan(4, 0, 0),
                                                 1);

        // Use the ToString method defined in WorkItem.
        Console.WriteLine(item.ToString());

        // Use the inherited Update method to change the title of the 
        // ChangeRequest object.
        change.Update("Change the Design of the Base Class",
            new TimeSpan(4, 0, 0));

        // ChangeRequest inherits WorkItem's override of ToString.
        Console.WriteLine(change.ToString());

        // Keep the console open in debug mode.
        Console.WriteLine("Press any key to exit.");
        Console.ReadKey();
    }
}
/* Output:
    1 - Fix Bugs
    2 - Change the Design of the Base Class
*/

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A

继承自

B

？而

A

是

class

，

class

是

public

，而

public class A

的主体是空的。鉴于到目前为止已经发布的答案，我不禁想知道这个问题背后是否还有更多你没有分享的东西。你在找更具体的东西吗？或者仅仅是基本的继承语法？要继续下面的所有解释，请阅读C#：Oy中有关继承的文档！“也许是个愚蠢的问题”：请不要为你不知道的事道歉！@David，我已经习惯了Java的语法，也就是“扩展”，我还没有用C语言编写过那么多程序，所以“：“只是把我弄糊涂了……非常感谢，所以这相当于Java的“扩展”？@Rosie是的！它们是等价的。看看这段代码，你会明白的。。嗨，索纳，太好了，非常感谢。我刚刚习惯了“C#”语法：）谢谢，我没有意识到这是继承，我习惯了java的“扩展”，所以“：”让我困惑：）