C#其他

Posted 2022-12-01 Vanau

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摘自：C#入门经典第10章
C#属性块

//---------Student.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace First

    public class Student
    
        public readonly string name;
        private double  score;
        public Student(string name)
        
            this.name = name;
            score = 0;       
        
        public override string ToString()
        
            return "[名字：" + this.name + "--分数：" + this.score + "]";
        
        public double stuScore
         
            get
            
                return score;
            
            set
            
                if (value >= 0 && value <= 100)
                    score = value;
                else
                    throw new ArgumentOutOfRangeException("stuScore",value,"stuScore must be assigned a value between 0 and 100!");     
            
         
    

//----------Program.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace First

    class Program
    
        static void Main(string[] args)
        
            Console.WriteLine("新建学生...");
            /*  //ERROR
            String[] nameList = new String[20];
            nameList="a","b","c";  
            */
            string[] nameList="张三","李四","王五";
            Student[] stu=new Student [3];
            stu[0] = new Student(nameList[0]);
            stu[1] = new Student(nameList[1]);
            stu[2] = new Student(nameList[2]);
            Console.WriteLine("stu 新建完成...");

            foreach(Student s in stu )
                try
                
                    Console.WriteLine("--------------------------");
                    Console.WriteLine("请给下面学生输入分数："+s.name);
                    double inputScore = Convert.ToDouble(Console.ReadLine());
                    s.stuScore = inputScore;
                    Console.WriteLine("设置分数成功！");
                
                catch (Exception e)
                
                    //Console.WriteLine("输入分数不符合要求！");                   
                
            Console.WriteLine("输出学生信息：");
            foreach (Student s in stu)
                Console.WriteLine(s);
            Console.ReadKey();
        
    

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摘自：C#入门经典第13章

C#委托和事件

//----------Connection.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Timers;

namespace Second

    //在名字空间声明一个委托.
    public delegate void MessageHandler(string message);   
    public class Connection
    
        /*
         * 在类中声明一个事件，且用关键字event修饰
         * public  event       MessageHandler      MessageArrived;
         *         关键字      委托（事件的类型）   事件
         */
        public event MessageHandler MessageArrived;
        private Timer pollTimer;
        public Connection()
        
            /*
             * 1.建立对象（这个对象可以引发事件Elapsed）
             * 2.订阅事件（采用显/隐式委托+=。这里的委托指ElapsedEventHandler，匹配方法是CheckMessage）
             * 3.开启线程（当引发事件后，就通知订阅器，转到相应的处理方法中去）
             * 注：在下面主线程中可以看到事件的嵌套
             */
            pollTimer = new Timer(100);
            pollTimer.Elapsed += new ElapsedEventHandler(CheckMessage);        
        
        public void Connect()
        
            pollTimer.Start();
        
        public void Disconnect()
        
            pollTimer.Stop();
        
        /*
         * 定义一个Random实例，生成0-9之间的随机数
         * 定义一个匹配方法CheckMessage，该方法与委托名具有相同的返回类型和形参
         * MessageArrived != null含义是：事件是否有订阅者？如果为null表示没有订阅，从而也就不会被引发
         * MessageArrived("Hello C sharp!");表示委托，由相应的匹配事件处理
         * 解释：见主函数
         */
        private static Random random = new Random();
        private void CheckMessage(object source,ElapsedEventArgs e)
        
            Console.WriteLine("Checking for new messages:");
            if ((random.Next(9) == 0) && (MessageArrived != null))
                MessageArrived("Hello C sharp!");    
        
    

//----------Display.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Second

    public class Display
    
        public void DisplayMessage(string message)
        
            Console.WriteLine("Message arrived:"+message );
        
    

//-------------Program.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Second

    class Program
    
        static void Main(string[] args)
        
            Connection myConnection = new Connection();
            Display myDisplay = new Display();
            /*
             * 事件触发者：Connection，事件触发对象：myConnection
             * 事件：MessageArrived，事件委托：MessageHandler
             * 
             * 事件订阅者：Display，事件订阅对象：myDisplay
             * 匹配方法：DisplayMessage，用来响应MessageArrived事件 
             */
            myConnection.MessageArrived += new MessageHandler(myDisplay.DisplayMessage);
            myConnection.Connect();
            Console.ReadKey();
            Console.ReadKey();