委托、 Lambda表达式和事件——委托

1. 简单示例
   

   /*
    * 由SharpDevelop创建。
    * 用户： David Huang
    * 日期: 2015/7/27
    * 时间: 10:22
    */
   using System;
   
   namespace Delegate_Book
   {
       class Program
       {
           delegate string GetAString();
           
           struct Currency
           {
               public uint Dollars;
               public ushort Cents;
               
               public Currency(uint Dollars,ushort Cents)
               {
                   this.Dollars=Dollars;
                   this.Cents=Cents;
               }
               
               public override string ToString()
               {
                   return string.Format("${0}.{1,2:00}",Dollars,Cents);
               } 
               
               public static string GetCurrencyUnit()
               {
                   return "Dollar";
               }
           }
           
           public static void Main(string[] args)
           {
               const int x = 5;
               //GetAString getAString =new GetAString(x.ToString);
               GetAString getAString=x.ToString;
               Console.WriteLine(getAString());     
               
               Currency currency=new Currency(50,60);
               getAString=currency.ToString;
               Console.WriteLine(getAString());
               
               Console.WriteLine(new GetAString(new Currency(50,50).ToString)());
               
               getAString=Currency.GetCurrencyUnit;
               Console.WriteLine(getAString());
               
               
               Console.Write("Press any key to continue . . . ");
               Console.ReadKey(true);
           }
       }
   }

2. Action<T>和Func<T>委 托
   

   /*
    * 由SharpDevelop创建。
    * 用户： David Huang
    * 日期: 2015/7/28
    * 时间: 14:31
    */
   using System;
   
   namespace MathOperations
   {
       static class MathOperations
       {
           public static double MutiplyByTwo(double value)
           {
               return 2*value;
           }
           
           public static double Square(double value)
           {
               return value*value;
           }
       }
       
       delegate double DoubleOp(double x);
       
       class Program
       {
           
           public static void Main(string[] args)
           {
               DoubleOp[] doubleOps={
                   MathOperations.MutiplyByTwo,
                   MathOperations.Square
               };
               
               foreach (var op in doubleOps) {
                   DoTheMath(op,2.5);
                   DoTheMath(op,3.5);
               }
               
               Func<double,double>[] doubleFuncs={
                   MathOperations.MutiplyByTwo,
                   MathOperations.Square
               };
               
               foreach (var func in doubleFuncs) {
                   DoTheFunc(func,2.5);
                   DoTheFunc(func,3.5);
               }
               
               Console.Write("Press any key to continue . . . ");
               Console.ReadKey(true);
           }
           
           static void DoTheMath(DoubleOp operation,double value)
           {
               double result=operation(value);
               Console.WriteLine(string.Format("vlaue is {0},result is {1}",value,result));
           }
           
           static void DoTheFunc(Func<double,double> func,double value)
           {
               var result = func(value);
               Console.WriteLine(string.Format("value is {0},result is {1}",value,result));
           }
           
       }
   }

3. 冒泡排序示例
   

   /*
    * 由SharpDevelop创建。
    * 用户： David Huang
    * 日期: 2015/7/29
    * 时间: 15:34
    */
   using System;
   using System.Linq;
   using System.Collections.Generic;
   
   namespace BubbleSorter
   {
       class Program
       {
           public static void Main(string[] args)
           {
               //int
               List<int> array=new List<int> {5,2,4,6,1};
               Sort(array);            
               Console.WriteLine(array.ConvertAll(i=>i.ToString()).Aggregate((current,next)=>string.Format("{0},{1}",current,next)).TrimEnd(','));
               
               //泛型
               List<int> list=new List<int> {5,2,4,6,1};
               Sort(list,IsBiggerThan);
               Console.WriteLine(array.ConvertAll(i=>i.ToString()).Aggregate((current,next)=>string.Format("{0},{1}",current,next)).TrimEnd(','));
               
               //泛型
               List<Person> personList=new List<Person>{
                   new Person{Name="Tom",Age=4},
                   new Person{Name="Jack",Age=2},
                   new Person{Name="Penny",Age=3},
                   new Person{Name="Lucy",Age=5}
               };
               Sort(personList,IsOlderThan);
               foreach (Person person in personList) {
                   Console.WriteLine(person);
               }
                          
               
               Console.Write("Press any key to continue . . . ");
               Console.ReadKey(true);
           }
           
           static bool IsOlderThan(Person p1,Person p2)
           {
               return p1.Age>p2.Age;
           }
           
           static bool IsBiggerThan(int a,int b)
           {
               return a>b;
           }
           
           static void Sort(IList<int> sortArray)
           {
               bool swapped=true;
               
               do
               {
                   swapped=false;
                   
                   for (int i = 0; i < sortArray.Count-1; i++) {
                       if (sortArray[i]>sortArray[i+1]) {
                           int tmp=sortArray[i];
                           sortArray[i]=sortArray[i+1];
                           sortArray[i+1]=tmp;
                           swapped=true;
                       }
                   }
                   
               }while (swapped);
           }
           
           static void Sort<T>(IList<T> list,Func<T,T,bool> comparison)
           {
               bool swapped=true;
               
               do{
                   swapped=false;
                   
                   for (int i = 0; i < list.Count-1; i++) {
                       if (comparison(list[i],list[i+1])) {
                           T temp=list[i];
                           list[i]=list[i+1];
                           list[i+1]=temp;
                           swapped=true;
                       }
                   }
                   
               }while(swapped);
           }
       }
       
       class Person
       {
           public string Name{get;set;}
           public int Age{get;set;}
           
           public override string ToString()
           {
               return string.Format("Name:{0},Age:{1}",Name,Age);
           }
       }
   }

4. 多播委托
   

   /*
    * 由SharpDevelop创建。
    * 用户： David Huang
    * 日期: 2015/7/30
    * 时间: 14:37
    */
   using System;
   
   namespace 多播
   {
       public static class MathOperations
       {
           public static void MutiplyByTwo(double value)
           {
               Console.WriteLine(string.Format("method: MutiplyByTwo, value: {0}, result: {1}",value,2*value));
           }
           
           public static void Square(double value)
           {
               Console.WriteLine(string.Format("method: Square, value: {0}, result: {1}",value,value*value));
           }
       }
       
       class Program
       {
           public static void Main(string[] args)
           {
               Action<double> mathOperations=MathOperations.MutiplyByTwo;
               mathOperations+=MathOperations.Square;
               
               DoTheMath(mathOperations,2.5);
               DoTheMath(mathOperations,3.5);
               
               Console.Write("Press any key to continue . . . ");
               Console.ReadKey(true);
           }
           
           static void DoTheMath(Action<double> action,double value)
           {
               action(value);
           }
       }
   }

5. 匿名委托
   

   /*
    * 由SharpDevelop创建。
    * 用户： David Huang
    * 日期: 2015/7/30
    * 时间: 16:19
    */
   using System;
   
   namespace 匿名
   {
       class Program
       {
           public static void Main(string[] args)
           {
               Func<int,int> anonDel=delegate(int i)
               {
                   return i*2;
               };
               
               
               Console.WriteLine(anonDel(4));
               // TODO: Implement Functionality Here
               
               Console.Write("Press any key to continue . . . ");
               Console.ReadKey(true);
           }
       }
   }