using System;
namespace HelloWorldApplication
{
   class HelloWorld
   {
      static void Main(string[] args)
      {
         /* 我的第一个 C# 程序*/
         Console.WriteLine("Hello World");
         Console.ReadKey();
      }
   }
}

using System;
namespace RectangleApplication
{
    class Rectangle
    {
        // 成员变量
        double length;
        double width;
        public void Acceptdetails()
        {
            length = 4.5;    
            width = 3.5;
        }
        public double GetArea()
        {
            return length * width;
        }
        public void Display()
        {
            Console.WriteLine("Length: {0}", length);
            Console.WriteLine("Width: {0}", width);
            Console.WriteLine("Area: {0}", GetArea());
        }
    }
    
    class ExecuteRectangle
    {
        static void Main(string[] args)
        {
            Rectangle r = new Rectangle();
            r.Acceptdetails();
            r.Display();
            Console.ReadLine();
        }
    }
}

using System;

namespace MyApp
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello, World!");
        }
    }
}

using System;

Console.WriteLine("Hello, World!");

object obj;
obj = 100; // 这是装箱
int a = (int)obj;//这是拆箱

using System;

namespace TypeConversionApplication
{
    class StringConversion
    {
        static void Main(string[] args)
        {
            // 定义一个整型变量
            int i = 75;
            
            // 定义一个浮点型变量
            float f = 53.005f;
            
            // 定义一个双精度浮点型变量
            double d = 2345.7652;
            
            // 定义一个布尔型变量
            bool b = true;

            // 将整型变量转换为字符串并输出
            Console.WriteLine(i.ToString());
            
            // 将浮点型变量转换为字符串并输出
            Console.WriteLine(f.ToString());
            
            // 将双精度浮点型变量转换为字符串并输出
            Console.WriteLine(d.ToString());
            
            // 将布尔型变量转换为字符串并输出
            Console.WriteLine(b.ToString());

            // 等待用户按键后关闭控制台窗口
            Console.ReadKey();
        }
    }
}

string str = "123.45";
double d = double.Parse(str);

string str = "123.45";
double d;
bool success = double.TryParse(str, out d);

if (success) {
    Console.WriteLine("转换成功: " + d);
} else {
    Console.WriteLine("转换失败");
}

using System;

public class Fahrenheit
{
    public double Degrees { get; set; }

    public Fahrenheit(double degrees)
    {
        Degrees = degrees;
    }

    // 隐式转换从Fahrenheit到double
    public static implicit operator double(Fahrenheit f)
    {
        return f.Degrees;
    }

    // 显式转换从double到Fahrenheit
    public static explicit operator Fahrenheit(double d)
    {
        return new Fahrenheit(d);
    }
}

public class Program
{
    public static void Main()
    {
        Fahrenheit f = new Fahrenheit(98.6);
        Console.WriteLine("Fahrenheit object: " + f.Degrees + " degrees");

        double temp = f; // 隐式转换
        Console.WriteLine("After implicit conversion to double: " + temp + " degrees");

        Fahrenheit newF = (Fahrenheit)temp; // 显式转换
        Console.WriteLine("After explicit conversion back to Fahrenheit: " + newF.Degrees + " degrees");
    }
}

int num;
num = Convert.ToInt32(Console.ReadLine());

212         /* 合法 */
215u        /* 合法 */
0xFeeL      /* 合法 */
078         /* 非法：8 不是一个八进制数字 */
032UU       /* 非法：不能重复后缀 */

3.14159       /* 合法 */
314159E-5L    /* 合法 */
510E          /* 非法：不完全指数 */
210f          /* 非法：没有小数或指数 */
.e55          /* 非法：缺少整数或小数 */

using System;

public class ConstTest 
{
    class SampleClass
    {
        public int x;
        public int y;
        public const int c1 = 5;
        public const int c2 = c1 + 5;

        public SampleClass(int p1, int p2) 
        {
            x = p1; 
            y = p2;
        }
    }

    static void Main()
    {
        SampleClass mC = new SampleClass(11, 22);
        Console.WriteLine("x = {0}, y = {1}", mC.x, mC.y);
        Console.WriteLine("c1 = {0}, c2 = {1}", 
                          SampleClass.c1, SampleClass.c2);
    }
}

            int a = 60;            /* 60 = 0011 1100 */  
            int b = 13;            /* 13 = 0000 1101 */
            int c = 0;          

             c = a & b;           /* 12 = 0000 1100 */
             Console.WriteLine("Line 1 - c 的值是 {0}", c );

             c = a | b;           /* 61 = 0011 1101 */
             Console.WriteLine("Line 2 - c 的值是 {0}", c);

             c = a ^ b;           /* 49 = 0011 0001 */
             Console.WriteLine("Line 3 - c 的值是 {0}", c);

             c = ~a;               /*-61 = 1100 0011 */
             Console.WriteLine("Line 4 - c 的值是 {0}", c);

             c = a << 2;     /* 240 = 1111 0000 */
             Console.WriteLine("Line 5 - c 的值是 {0}", c);

             c = a >> 2;     /* 15 = 0000 1111 */

foreach (var item in collection)
{
    // 循环
}

class NumberManipulator
{
    public void swap(ref int x, ref int y)
    {
        int temp;
        temp = x;
        x = y;
        y = temp;
    }

    static void Main(string[] args)
    {
        NumberManipulator n = new NumberManipulator();
        int a = 50;
        int b = 100;
        Console.WriteLine("在交换之前，a 的值： {0}", a);
        Console.WriteLine("在交换之前，b 的值： {0}", b);
        n.swap(ref a, ref b);
        Console.WriteLine("在交换之后，a 的值： {0}", a);
        Console.WriteLine("在交换之后，b 的值： {0}", b);

        Console.ReadLine();
    }
}

 public void GetValue(out int x)
 {
     int temp = 54;
     x = temp; ;
 }

 static void Main(string[] args)
 {
     NumberManipulator n = new NumberManipulator();
     /* 局部变量定义 */
     int a = 100;

     Console.WriteLine("在方法调用之前，a 的值： {0}", a);

     /* 调用函数来获取值 */
     n.GetValue(out a);

     Console.WriteLine("在方法调用之后，a 的值： {0}", a);
     Console.ReadLine();
 }

int? i = 3;
// 等价于
Nullable<int> i = new Nullable<int>(3);

// 默认值0
int i ;
// 默认值null
int? ii;

static void Main(string[] args)
      {
         int? num1 = null;
         int? num2 = 45;
         double? num3 = new double?();
         double? num4 = 3.14157;       
         bool? boolval = new bool?();
     
         Console.WriteLine("显示可空类型的值： {0}, {1}, {2}, {3}",
                            num1, num2, num3, num4);
         Console.WriteLine("一个可空的布尔值： {0}", boolval);
         Console.ReadLine();
      }

int? num1 = null;
           
double num3;
num3 = num1 ?? 5.34;

int [,] a = new int [3,4] {
 {0, 1, 2, 3} ,   /*  初始化索引号为 0 的行 */
 {4, 5, 6, 7} ,   /*  初始化索引号为 1 的行 */
 {8, 9, 10, 11}   /*  初始化索引号为 2 的行 */
};

int[,] a = new int[5, 2] { { 0, 0 }, { 1, 2 }, { 2, 4 }, { 3, 6 }, { 4, 8 } };
int i, j;
for(i=0;i < 5; i++)
{
    for(j = 0; j < 2; j++)
    {
        Console.Write(a[i,j] + "\t");
    }
    Console.WriteLine() ;
}

int [][] socres;

int[][] scores = new int[5][];
for (int i = 0; i < scores.Length; i++) 
{
   scores[i] = new int[4];
}

int[][] scores = new int[2][]{new int[]{92,93,94},new int[]{85,66,87,88}};

int[][] a = new int[][] { new int[] { 0, 0 }, new int[] { 1, 2 }, new int[] { 2, 4, 6 }, new int[] { 3, 6 }, new int[] { 4, 8 } };
for (int i = 0; i < a.Length; i++)
{
    int[] temp = a[i]; 
    for(int j = 0;j < temp.Length; j++)
    {
        Console.Write(temp[j] + "\t");
    }
    Console.WriteLine() ;
}

void GetAverage(int[] arr, out double res)
{
    int sum = 0;
    for (int i = 0; i < arr.Length; i++)
    {
        sum += arr[i];
    }
    res = (double)sum / arr.Length;
}
void RedefineArr(int[] arr)
{
    for (int i = 0; i < arr.Length; i++)
    {
        arr[i] += 1000;
    }
}
static void Main(string[] args)
{
    MyArray app = new MyArray(); 
    int[] arr = { 1000, 2, 3, 17, 50 };
    double avg;
    app.GetAverage(arr,out avg);
    Console.WriteLine(avg);
    app.RedefineArr(arr);
 	Array.ForEach(arr, a => { Console.Write(a + "\t"); });
}

public int AddElements(params int[] arr)
{
    int sum = 0;
    foreach (int i in arr)
    {
       sum += i;
    }
    return sum;
}
static void Main(string[] args)
{
	ParamArray app = new ParamArray();
	int sum = app.AddElements(512, 720, 250, 567, 889);
	Console.WriteLine("总和是： {0}", sum);
	int[] arr = { 1000, 2, 3, 17, 50 };
	sum = app.AddElements(arr);
	Console.WriteLine("总和是： {0}", sum);
}

            // 字符拼接
            string fname, lname;
            fname = "Roa";
            lname = "ss";
            string fullname = fname + lname;
            Console.WriteLine("Full Name: {0}", fullname);
            //通过使用 string 构造函数
            char[] letters = { 'H', 'e', 'l', 'l', 'o' };
            string greetings = new string(letters);
            Console.WriteLine("Greetings: {0}", greetings);
            //方法返回字符串
            string[] sarray = { "Hello", "From", "Tutorials", "Point" };
            string message = String.Join(" ", sarray);
            Console.WriteLine("Message: {0}", message);

            //用于转化值的格式化方法
            DateTime waiting = new DateTime();
            waiting = DateTime.Now;
            string chat = String.Format("Message sent at {0:t} on {0:D}",
            waiting);
            Console.WriteLine("Message: {0}", chat);

struct Books
{
   public string title;
   public string author;
   public string subject;
   public int book_id;
};  

enum <enum_name>
{ 
    enumeration list 
};

<access specifier> class  class_name
{
    // member variables
    <access specifier> <data type> variable1;
    ...
    <access specifier> <data type> variableN;
    // member methods
    <access specifier> <return type> method1(parameter_list)
    {
        // method body
    }
    ...
    <access specifier> <return type> methodN(parameter_list)
    {
        // method body
    }
}

<访问修饰符> class <基类>
{
 ...
}
class <派生类> : <基类>
{
 ...
}

using System;
namespace RectangleApplication
{
   class Rectangle
   {
      // 成员变量
      protected double length;
      protected double width;
      public Rectangle(double l, double w)
      {
         length = l;
         width = w;
      }
      public double GetArea()
      {
         return length * width;
      }
      public void Display()
      {
         Console.WriteLine("长度： {0}", length);
         Console.WriteLine("宽度： {0}", width);
         Console.WriteLine("面积： {0}", GetArea());
      }
   }//end class Rectangle  
   class Tabletop : Rectangle
   {
      private double cost;
      public Tabletop(double l, double w) : base(l, w)
      { }
      public double GetCost()
      {
         double cost;
         cost = GetArea() * 70;
         return cost;
      }
      public void Display()
      {
         base.Display();
         Console.WriteLine("成本： {0}", GetCost());
      }
   }
   class ExecuteRectangle
   {
      static void Main(string[] args)
      {
         Tabletop t = new Tabletop(4.5, 7.5);
         t.Display();
         Console.ReadLine();
      }
   }
}

interface IBaseInterface
{
    void Method1();
}

interface IDerivedInterface : IBaseInterface
{
    void Method2();
}

using System;

// 定义一个基接口
interface IBaseInterface
{
    void Method1();
}

// 定义一个派生接口，继承自基接口
interface IDerivedInterface : IBaseInterface
{
    void Method2();
}

// 实现派生接口的类
class MyClass : IDerivedInterface
{
    public void Method1()
    {
        Console.WriteLine("Method1 implementation");
    }

    public void Method2()
    {
        Console.WriteLine("Method2 implementation");
    }
}

class Program
{
    static void Main(string[] args)
    {
        // 创建 MyClass 类的实例
        MyClass obj = new MyClass();

        // 调用继承自基接口的方法
        obj.Method1();

        // 调用派生接口新增的方法
        obj.Method2();
    }
}

using System;
namespace InheritanceApplication
{
   class Shape 
   {
      public void setWidth(int w)
      {
         width = w;
      }
      public void setHeight(int h)
      {
         height = h;
      }
      protected int width;
      protected int height;
   }

   // 基类 PaintCost
   public interface PaintCost 
   {
      int getCost(int area);

   }
   // 派生类
   class Rectangle : Shape, PaintCost
   {
      public int getArea()
      {
         return (width * height);
      }
      public int getCost(int area)
      {
         return area * 70;
      }
   }
   class RectangleTester
   {
      static void Main(string[] args)
      {
         Rectangle Rect = new Rectangle();
         int area;
         Rect.setWidth(5);
         Rect.setHeight(7);
         area = Rect.getArea();
         // 打印对象的面积
         Console.WriteLine("总面积： {0}",  Rect.getArea());
         Console.WriteLine("油漆总成本： ${0}" , Rect.getCost(area));
         Console.ReadKey();
      }
   }
}

using System;
namespace PolymorphismApplication
{
   abstract class Shape
   {
       abstract public int area();
   }
   class Rectangle:  Shape
   {
      private int length;
      private int width;
      public Rectangle( int a=0, int b=0)
      {
         length = a;
         width = b;
      }
      public override int area ()
      { 
         Console.WriteLine("Rectangle 类的面积：");
         return (width * length); 
      }
   }

   class RectangleTester
   {
      static void Main(string[] args)
      {
         Rectangle r = new Rectangle(10, 7);
         double a = r.area();
         Console.WriteLine("面积： {0}",a);
         Console.ReadKey();
      }
   }
}

public class Shape
{
    public int X { get; private set; }
    public int Y { get; private set; }
    public int Height { get; set; }
    public int Width { get; set; }
   
    // 虚方法
    public virtual void Draw()
    {
        Console.WriteLine("执行基类的画图任务");
    }
}

class Circle : Shape
{
    public override void Draw()
    {
        Console.WriteLine("画一个圆形");
        base.Draw();
    }
}
class Rectangle : Shape
{
    public override void Draw()
    {
        Console.WriteLine("画一个长方形");
        base.Draw();
    }
}
class Triangle : Shape
{
    public override void Draw()
    {
        Console.WriteLine("画一个三角形");
        base.Draw();
    }
}

class Program
{
    static void Main(string[] args)
    {
        // 创建一个 List<Shape> 对象，并向该对象添加 Circle、Triangle 和 Rectangle
        var shapes = new List<Shape>
        {
            new Rectangle(),
            new Triangle(),
            new Circle()
        };

        // 使用 foreach 循环对该列表的派生类进行循环访问，并对其中的每个 Shape 对象调用 Draw 方法
        foreach (var shape in shapes)
        {
            shape.Draw();
        }

        Console.WriteLine("按下任意键退出。");
        Console.ReadKey();
    }
}

class Box
   {
      private double length;      // 长度
      private double breadth;     // 宽度
      private double height;      // 高度

      public double getVolume()
      {
         return length * breadth * height;
      }
      public void setLength( double len )
      {
         length = len;
      }

      public void setBreadth( double bre )
      {
         breadth = bre;
      }

      public void setHeight( double hei )
      {
         height = hei;
      }
      // 重载 + 运算符来把两个 Box 对象相加
      public static Box operator+ (Box b, Box c)
      {
         Box box = new Box();
         box.length = b.length + c.length;
         box.breadth = b.breadth + c.breadth;
         box.height = b.height + c.height;
         return box;
      }
   }

using System;

interface IMyInterface
{
        // 接口成员
    void MethodToImplement();
}

class InterfaceImplementer : IMyInterface
{
    static void Main()
    {
        InterfaceImplementer iImp = new InterfaceImplementer();
        iImp.MethodToImplement();
    }

    public void MethodToImplement()
    {
        Console.WriteLine("MethodToImplement() called.");
    }
}

#define DEBUG

#if DEBUG
    Console.WriteLine("Debug mode");
#elif RELEASE
    Console.WriteLine("Release mode");
#else
    Console.WriteLine("Other mode");
#endif

#warning This is a warning message
#error This is an error message

#region MyRegion
    // Your code here
#endregion

#line 100 "MyFile.cs"
    // The next line will be reported as line 100 in MyFile.cs
    Console.WriteLine("This is line 100");
#line default
    // Line numbering returns to normal

#pragma warning disable 414
    private int unusedVariable;
#pragma warning restore 414

#nullable enable
    string? nullableString = null;
#nullable disable

#define DEBUG
#define VC_V10
using System;
public class TestClass
{
   public static void Main()
   {

      #if (DEBUG && !VC_V10)
         Console.WriteLine("DEBUG is defined");
      #elif (!DEBUG && VC_V10)
         Console.WriteLine("VC_V10 is defined");
      #elif (DEBUG && VC_V10)
         Console.WriteLine("DEBUG and VC_V10 are defined");
      #else
         Console.WriteLine("DEBUG and VC_V10 are not defined");
      #endif
      Console.ReadKey();
   }
}

using System;
namespace UserDefinedException
{
   class TestTemperature
   {
      static void Main(string[] args)
      {
         Temperature temp = new Temperature();
         try
         {
            temp.showTemp();
         }
         catch(TempIsZeroException e)
         {
            Console.WriteLine("TempIsZeroException: {0}", e.Message);
         }
         Console.ReadKey();
      }
   }
}
public class TempIsZeroException: ApplicationException
{
   public TempIsZeroException(string message): base(message)
   {
   }
}
public class Temperature
{
   int temperature = 0;
   public void showTemp()
   {
      if(temperature == 0)
      {
         throw (new TempIsZeroException("Zero Temperature found"));
      }
      else
      {
         Console.WriteLine("Temperature: {0}", temperature);
      }
   }
}

FileStream <object_name> = new FileStream( <file_name>,
<FileMode Enumerator>, <FileAccess Enumerator>, <FileShare Enumerator>);

FileStream F = new FileStream("sample.txt", FileMode.Open, FileAccess.Read, FileShare.Read);

using System;
using System.IO;

namespace FileIOApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            FileStream F = new FileStream("test.dat", 
            FileMode.OpenOrCreate, FileAccess.ReadWrite);

            for (int i = 1; i <= 20; i++)
            {
                F.WriteByte((byte)i);
            }

            F.Position = 0;

            for (int i = 0; i <= 20; i++)
            {
                Console.Write(F.ReadByte() + " ");
            }
            F.Close();
            Console.ReadKey();
        }
    }
}

void readTextFile()
{
    try
    {
        using (StreamReader sr = new StreamReader
             ("E:\\Code\\C#Learn\\Basic\\HelloWorld\\HelloWorld\\Text.txt", System.Text.Encoding.UTF8))
        {
            ;
            string line;
            while ((line = sr.ReadLine()) != null)
            {
                Console.WriteLine(line);
            }

        }
    }
    catch (Exception e)
    {
        Console.WriteLine("The file could not be read:");
        Console.WriteLine(e.Message);
    }
}

void writeTextFile()
{
    string[] names = new string[] { "Zara Ali", "Nuha Ali" };
    using (StreamWriter sw = new StreamWriter("names.txt"))
    {
        foreach (string s in names)
        {
            sw.WriteLine(s);

        }
    }

    // 从文件中读取并显示每行
    string line = "";
    using (StreamReader sr = new StreamReader("names.txt"))
    {
        while ((line = sr.ReadLine()) != null)
        {
            Console.WriteLine(line);
        }
    }
}

BinaryWriter bw;
BinaryReader br;
int i = 25;
double d = 3.14157;
bool b = true;
string s = "i am happy";
// 创建文件
try
{
    bw = new BinaryWriter(new FileStream("bindata", FileMode.OpenOrCreate, FileAccess.Write));
}
catch (IOException e)
{
    Console.WriteLine(e.Message + "\n Cannot create file.");
    return;
}
// 写入文件
try
{
    bw.Write(i);
    bw.Write(d);
    bw.Write(b);
    bw.Write(s);
}
catch (IOException e)
{
    Console.WriteLine(e.Message + "\n Cannot write to file.");
    return;
}
bw.Close();
// 读取文件
try
{
    br = new BinaryReader(new FileStream("bindata", FileMode.Open, FileAccess.Read));
}
catch (IOException e) {
    Console.WriteLine(e.Message + "\n Cannot open file.");
    return;
}
try
{
    i = br.ReadInt32();
    Console.WriteLine("Integer data: {0}", i);
    d = br.ReadDouble();
    Console.WriteLine("Double data: {0}", d);
    b = br.ReadBoolean();
    Console.WriteLine("Boolean data: {0}", b);
    s = br.ReadString();
    Console.WriteLine("String data: {0}", s);
}
catch (IOException e)
{
    Console.WriteLine(e.Message + "\n Cannot read from file.");
    return;
}
br.Close();

[attribute(positional_parameters, name_parameter = value, ...)]
element

[AttributeUsage(
   validon,
   AllowMultiple=allowmultiple,
   Inherited=inherited
)]

[Conditional(
   conditionalSymbol
)]

[Conditional("DEBUG")]

[Obsolete(
   message
)]
[Obsolete(
   message,
   iserror
)]

using System;
public class MyClass
{
   [Obsolete("Don't use OldMethod, use NewMethod instead", true)]
   static void OldMethod()
   { 
      Console.WriteLine("It is the old method");
   }
   static void NewMethod()
   { 
      Console.WriteLine("It is the new method"); 
   }
   public static void Main()
   {
      OldMethod();
   }
}

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Constructor |AttributeTargets.Field |AttributeTargets.Method |AttributeTargets.Property,AllowMultiple = true)]
class DebugInfo : System.Attribute
{

}

[AttributeUsage(AttributeTargets.Class |
AttributeTargets.Constructor |
AttributeTargets.Field |
AttributeTargets.Method |
AttributeTargets.Property,
AllowMultiple = true)]

public class DeBugInfo : System.Attribute
{
  private int bugNo;
  private string developer;
  private string lastReview;
  public string message;

  public DeBugInfo(int bg, string dev, string d)
  {
      this.bugNo = bg;
      this.developer = dev;
      this.lastReview = d;
  }

  public int BugNo
  {
      get
      {
          return bugNo;
      }
  }
  public string Developer
  {
      get
      {
          return developer;
      }
  }
  public string LastReview
  {
      get
      {
          return lastReview;
      }
  }
  public string Message
  {
      get
      {
          return message;
      }
      set
      {
          message = value;
      }
  }
}

[DebugInfo(45, "ME", "29292/12/2", Message = "Rectangle")]
class Rectangle
{
    [DebugInfo(43, "ME", "29292/12/2", Message = "成员变量")]
    protected double length;
    protected double width;
    public Rectangle(double l, double w)
    {
        length = l;
        width = w;
    }
    [DebugInfo(55, "Zara Ali", "19/10/2012", Message = "Return type mismatch")]
    public double GetArea()
    {
        return length * width;
    }
    [DebugInfo(56, "Zara Ali", "19/10/2012")]
    public void Display()
    {
        Console.WriteLine("Length: {0}", length);
        Console.WriteLine("Width: {0}", width);
        Console.WriteLine("Area: {0}", GetArea());
    }
}

System.Reflection.MemberInfo info = typeof(Rectangle);
object[] attributes = info.GetCustomAttributes(true);
for (int i = 0; i < attributes.Length; i++)
{
    System.Console.WriteLine(attributes[i]);
}

static void Main(string[] args)
{
    Rectangle r = new Rectangle(4.5, 7.5);
    //r.Display();
    Type type = typeof(Rectangle); 
    // 遍历类特性
    foreach(Object attributes in type.GetCustomAttributes(false)){
            DebugInfo dbi = (DebugInfo)attributes;
        if (dbi != null)
        {
            Console.WriteLine("Bug no: {0}", dbi.BugNo);
            Console.WriteLine("Developer: {0}", dbi.Developer);
            Console.WriteLine("Last Reviewed: {0}",
                                     dbi.LastReview);
            Console.WriteLine("Remarks: {0}", dbi.Message);
        }
    }

    // 遍历方法特性
    foreach (MethodInfo m in type.GetMethods())
    {
        foreach (Attribute a in m.GetCustomAttributes(true))
        {
            DebugInfo dbi = a as DebugInfo;
            if (null != dbi)
            {
                Console.WriteLine("Bug no: {0}, for Method: {1}",
                                              dbi.BugNo, m.Name);
                Console.WriteLine("Developer: {0}", dbi.Developer);
                Console.WriteLine("Last Reviewed: {0}",
                                              dbi.LastReview);
                Console.WriteLine("Remarks: {0}", dbi.Message);
            }
        }
    }

    // 遍历字段特性
    foreach (FieldInfo f in type.GetFields(BindingFlags.NonPublic | BindingFlags.Instance))
    {
        foreach (Attribute a in f.GetCustomAttributes(true))
        {
            DebugInfo dbi = a as DebugInfo;
            if (dbi != null)
            {
                Console.WriteLine("Bug no: {0}, for Field: {1}", dbi.BugNo, f.Name);
                Console.WriteLine("Developer: {0}", dbi.Developer);
                Console.WriteLine("Last Reviewed: {0}", dbi.LastReview);
                Console.WriteLine("Remarks: {0}", dbi.Message);
            }
        }
    }
}

public class Person
{
    private string name;

    public string Name
    {
        get { return name; }
        set { name = value; }
    }
}

public class Person
{
    public string Name { get; set; }
}

element-type this[int index]
{
   // get 访问器
   get
   {
      // 返回 index 指定的值
   }

   // set 访问器
   set
   {
      // 设置 index 指定的值
   }
}

    class IndexedNames
    {
        private string[] namelist = new string[size];
        static public int size = 10;
        public IndexedNames()
        {
            for (int i = 0; i < size; i++)
                namelist[i] = "N. A.";
        }

        public string this[int index]
        {
            get
            {
                string temp;
                if (index >= 0 && index < size)
                {
                    temp = namelist[index];
                }
                else
                {
                    temp = "";
                }
                return temp;
            }
            set
            {
                if (index >= 0 && index < size) { namelist[index] = value; }
            }
        }
    }

public string this[int index]
{
    get
    {
        string temp;
        if (index >= 0 && index < size)
        {
            temp = namelist[index];
        }
        else
        {
            temp = "";
        }
        return temp;
    }
    set
    {
        if (index >= 0 && index < size) { namelist[index] = value; }
    }
}

public int this[string name]
{
    get
    {
        int index = 0;
        while (index < size)
        {
            if (namelist[index] == name)
            {
                return index;
            }
            index++;
        }
        return index == size ? 0 : index;
    }
}

delegate <return type> <delegate-name> <parameter list>

public delegate void printString(string s);
...
printString ps1 = new printString(WriteToScreen);
printString ps2 = new printString(WriteToFile);

class TestDelegate
{
    static int num = 10;
    public static int AddNum(int p)
    {
        num += p;
        return num; 
    }

    public static int MultNum(int q)
    {
        num *= q;
        return num;
    }
    public static int getNum()
    {
        return num;
    }

    static void Main(string[] args)
    {
        // 创建委托实例
        NumberChanger nc1 = new NumberChanger(AddNum);
        NumberChanger nc2 = new NumberChanger(MultNum);
        // 使用委托对象调用方法
        nc1(25);
        Console.WriteLine("Value of Num: {0}", getNum());
        nc2(5);
        Console.WriteLine("Value of Num: {0}", getNum());
    }
}

        static void Main(string[] args)
        {
            // 多播
            NumberChanger nc;
            NumberChanger nc1 = new NumberChanger(AddNum);
            NumberChanger nc2 = new NumberChanger(MultNum);
            nc = nc1;
            nc += nc2;
            nc(5);
            Console.WriteLine("Value of Num: {0}", getNum());
        }

using System;
using System.IO;

namespace DelegateAppl
{
   class PrintString
   {
      static FileStream fs;
      static StreamWriter sw;
      // 委托声明
      public delegate void printString(string s);

      // 该方法打印到控制台
      public static void WriteToScreen(string str)
      {
         Console.WriteLine("The String is: {0}", str);
      }
      // 该方法打印到文件
      public static void WriteToFile(string s)
      {
         fs = new FileStream("c:\\message.txt", FileMode.Append, FileAccess.Write);
         sw = new StreamWriter(fs);
         sw.WriteLine(s);
         sw.Flush();
         sw.Close();
         fs.Close();
      }
      // 该方法把委托作为参数，并使用它调用方法
      public static void sendString(printString ps)
      {
         ps("Hello World");
      }
      static void Main(string[] args)
      {
          // 可以用多播
         printString ps1 = new printString(WriteToScreen);
         printString ps2 = new printString(WriteToFile);
         sendString(ps1);
         sendString(ps2);
         Console.ReadKey();
      }
   }
}

public delegate void BoilerLogHandler(string status);

// 基于上面的委托定义事件
public event BoilerLogHandler BoilerEventLog;

    // 1. 定义一个委托类型
    internal delegate void NotifyEventHandler(object sender, EventArgs e);

    // publisher
    class ProcessBusinessLogic
    {
        // 2. 声明事件
        public event NotifyEventHandler ProcessCompleted;

        // 3. 触发事件
        protected virtual void OnProcessCompleted(EventArgs e)
        {
            // ?.Invoke确保只有在有订阅者时才调用事件
            ProcessCompleted?.Invoke(this, e);
        }

        // 模拟触发事件的过程
        public void StartProcess()
        {
            Console.WriteLine("Process started");
            // 执行逻辑代码...

            // 触发事件
            OnProcessCompleted(EventArgs.Empty);
        }
    }

    // subscriber
    class EventSubscriber
    {
        public void Subscribe(ProcessBusinessLogic process)
        {
            // 4. 订阅事件
            process.ProcessCompleted += Process_ProcessCompleted;
        }
        // 事件的处理
        private void Process_ProcessCompleted(object sender, EventArgs e)
        {
            Console.WriteLine("Process Completed!");
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            // 事件发布者
            ProcessBusinessLogic process = new ProcessBusinessLogic();
            // 事件接收者
            EventSubscriber subscriber = new EventSubscriber();
            // 订阅事件
            subscriber.Subscribe(process);
            // 启动
            process.StartProcess();
        }
    }

    class EventTest
    {
        private int value;
        public delegate void NumMainpulationHandler();

        public event NumMainpulationHandler ChangeNum;

        protected virtual void OnNumChanged()
        {
            if (ChangeNum != null)
            {
                // 触发事件
                ChangeNum();
            }
            else
            {
                Console.WriteLine("event not fire");
            }
        }

        public EventTest()
        {
            int n = 5;
            SetValue(n);
        }
        public void SetValue(int n)
        {
            if (value != n)
            {
                value = n;
                OnNumChanged();
            }
        }

    }

    // subscriber
    public class subscribEvent
    {
        public void printf()
        {
            Console.WriteLine("event fire");
            Console.ReadKey();
        }
    }

    class MainClass
    {
        static void Main(string[] args)
        {
            EventTest e = new EventTest();
            subscribEvent v = new subscribEvent();
            e.ChangeNum += new EventTest.NumMainpulationHandler(v.printf);
            e.SetValue(7);
            e.SetValue(11);
        }
    }

namespace BoilerEventApplication
{
    class Boiler
    {
        public int Temp { get; private set; }
        public int Pressure { get; private set; }

        public Boiler(int temp, int pressure)
        {
            Temp = temp;
            Pressure = pressure;
        }
    }

    // 事件发布器
    public class DelegateBoilerEvent
    {
        public delegate void BoilerLogHandler(string status);

        // 定义事件
        public event BoilerLogHandler BoilerEventLog;
        protected void OnBoilerEventLog(string message)
        {
            BoilerEventLog?.Invoke(message);
        }

        public void LogProgress()
        {
            string remarks = "O.K.";
            Boiler boiler = new Boiler(100, 12);
            int temp = boiler.Temp;
            int pressure = boiler.Pressure;
            if (temp > 150 || temp < 80 || pressure < 12 || pressure > 15)
            {
                remarks = "Need Maintenance";
            }
            OnBoilerEventLog($"Logging Info:\nTemperature: {temp}\nPressure: {pressure}\nMessage: {remarks}");
        }
    }
    // 该类用于写入文件
    class BoilerInfoLogger : IDisposable
    {
        private readonly StreamWriter _streamWriter;

        public BoilerInfoLogger(string filename)
        {
            _streamWriter = new StreamWriter(new FileStream(filename, FileMode.Append, FileAccess.Write));
        }

        public void Logger(string info)
        {
            _streamWriter.WriteLine(info);
        }

        public void Dispose()
        {
            _streamWriter?.Close();
        }
    }

    // 事件订阅器
    public class RecordBoilerInfo
    {
        static void Logger(string info)
        {
            Console.WriteLine(info);
        }

        static void Main(string[] args)
        {
            using (BoilerInfoLogger fileLogger = new BoilerInfoLogger("boiler.txt"))
            {
                DelegateBoilerEvent boilerEvent = new DelegateBoilerEvent();
                boilerEvent.BoilerEventLog += Logger;
                boilerEvent.BoilerEventLog += fileLogger.Logger;
                boilerEvent.LogProgress();
            }
        }
    }
}

using System;
using System.Collections;

namespace CollectionApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            ArrayList al = new ArrayList();

            Console.WriteLine("Adding some numbers:");
            al.Add(45);
            al.Add(78);
            al.Add(33);
            al.Add(56);
            al.Add(12);
            al.Add(23);
            al.Add(9);
            
            Console.WriteLine("Capacity: {0} ", al.Capacity);
            Console.WriteLine("Count: {0}", al.Count);
                      
            Console.Write("Content: ");
            foreach (int i in al)
            {
                Console.Write(i + " ");
            }
            Console.WriteLine();
            Console.Write("Sorted Content: ");
            al.Sort();
            foreach (int i in al)
            {
                Console.Write(i + " ");
            }
            Console.WriteLine();
            Console.ReadKey();
        }
    }
}

using System;
using System.Collections;

namespace CollectionsApplication
{
   class Program
   {
      static void Main(string[] args)
      {
         Hashtable ht = new Hashtable();


         ht.Add("001", "Zara Ali");
         ht.Add("002", "Abida Rehman");
         ht.Add("003", "Joe Holzner");
         ht.Add("004", "Mausam Benazir Nur");
         ht.Add("005", "M. Amlan");
         ht.Add("006", "M. Arif");
         ht.Add("007", "Ritesh Saikia");

         if (ht.ContainsValue("Nuha Ali"))
         {
            Console.WriteLine("This student name is already in the list");
         }
         else
         {
            ht.Add("008", "Nuha Ali");
         }
         // 获取键的集合 
         ICollection key = ht.Keys;

         foreach (string k in key)
         {
            Console.WriteLine(k + ": " + ht[k]);
         }
         Console.ReadKey();
      }
   }
}

using System;
using System.Collections;

namespace CollectionsApplication
{
   class Program
   {
      static void Main(string[] args)
      {
         SortedList sl = new SortedList();

         sl.Add("001", "Zara Ali");
         sl.Add("002", "Abida Rehman");
         sl.Add("003", "Joe Holzner");
         sl.Add("004", "Mausam Benazir Nur");
         sl.Add("005", "M. Amlan");
         sl.Add("006", "M. Arif");
         sl.Add("007", "Ritesh Saikia");

         if (sl.ContainsValue("Nuha Ali"))
         {
            Console.WriteLine("This student name is already in the list");
         }
         else
         {
            sl.Add("008", "Nuha Ali");
         }

         // 获取键的集合 
         ICollection key = sl.Keys;

         foreach (string k in key)
         {
            Console.WriteLine(k + ": " + sl[k]);
         }
      }
   }
}

using System;
using System.Collections;

namespace CollectionsApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            Stack st = new Stack();

            st.Push('A');
            st.Push('M');
            st.Push('G');
            st.Push('W');
            
            Console.WriteLine("Current stack: ");
            foreach (char c in st)
            {
                Console.Write(c + " ");
            }
            Console.WriteLine();
            
            st.Push('V');
            st.Push('H');
            Console.WriteLine("The next poppable value in stack: {0}", 
            st.Peek());
            Console.WriteLine("Current stack: ");           
            foreach (char c in st)
            {
               Console.Write(c + " ");
            }
            Console.WriteLine();

            Console.WriteLine("Removing values ");
            st.Pop();
            st.Pop();
            st.Pop();
            
            Console.WriteLine("Current stack: ");
            foreach (char c in st)
            {
               Console.Write(c + " "); 
            }
        }
    }
}

using System;
using System.Collections;

namespace CollectionsApplication
{
   class Program
   {
      static void Main(string[] args)
      {
         Queue q = new Queue();

         q.Enqueue('A');
         q.Enqueue('M');
         q.Enqueue('G');
         q.Enqueue('W');
         
         Console.WriteLine("Current queue: ");
         foreach (char c in q)
            Console.Write(c + " ");
         Console.WriteLine();
         q.Enqueue('V');
         q.Enqueue('H');
         Console.WriteLine("Current queue: ");         
         foreach (char c in q)
            Console.Write(c + " ");
         Console.WriteLine();
         Console.WriteLine("Removing some values ");
         char ch = (char)q.Dequeue();
         Console.WriteLine("The removed value: {0}", ch);
         ch = (char)q.Dequeue();
         Console.WriteLine("The removed value: {0}", ch);
         Console.ReadKey();
      }
   }
}

using System;
using System.Collections;

namespace CollectionsApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            // 创建两个大小为 8 的点阵列
            BitArray ba1 = new BitArray(8);
            BitArray ba2 = new BitArray(8);
            byte[] a = { 60 };
            byte[] b = { 13 };
            
            // 把值 60 和 13 存储到点阵列中
            ba1 = new BitArray(a);
            ba2 = new BitArray(b);

            // ba1 的内容
            Console.WriteLine("Bit array ba1: 60");
            for (int i = 0; i < ba1.Count; i++)
            {
                Console.Write("{0, -6} ", ba1[i]);
            }
            Console.WriteLine();
            
            // ba2 的内容
            Console.WriteLine("Bit array ba2: 13");
            for (int i = 0; i < ba2.Count; i++)
            {
                Console.Write("{0, -6} ", ba2[i]);
            }
            Console.WriteLine();
           
            
            BitArray ba3 = new BitArray(8);
            ba3 = ba1.And(ba2);

            // ba3 的内容
            Console.WriteLine("Bit array ba3 after AND operation: 12");
            for (int i = 0; i < ba3.Count; i++)
            {
                Console.Write("{0, -6} ", ba3[i]);
            }
            Console.WriteLine();

            ba3 = ba1.Or(ba2);
            // ba3 的内容
            Console.WriteLine("Bit array ba3 after OR operation: 61");
            for (int i = 0; i < ba3.Count; i++)
            {
                Console.Write("{0, -6} ", ba3[i]);
            }
            Console.WriteLine();
            
            Console.ReadKey();
        }
    }
}