匿名表达式，lambda表达式，Linq的示例

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.Threading;

namespace MethodDelegateLamda

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}

//示例1,使用线程

private void button1_Click(object sender, EventArgs e)

{

//csharp 1.0

//使用委托，使用已定义好的函数

new Thread(new ThreadStart(MyFun)).Start();

//csharp 2.0

//省略委托：MyFun自动实例化为ThreadStart委托（

new Thread(MyFun).Start();

//匿名方法

new Thread(new ThreadStart( delegate(){ Console.Write("my function"); })).Start();

//匿名方法，省略参数列表

new Thread(new ThreadStart( delegate{ Console.Write("my function"); })).Start();

//匿名方法，自动转委托

new Thread( delegate(){ Console.Write("my function"); }).Start();

//csharp 3.0

//Lambda表达式

new Thread(() => { Console.Write("my function"); }).Start();

}

void MyFun()

{

Console.Write("my function");

}

//示例2,使用事件

private void button3_Click(object sender, EventArgs e)

{

Example3();

}

void Example3()

{

//csharp 1.0

//使用委托，使用自定义函数

this.MouseMove += new MouseEventHandler(Form1_MouseMove);

//csharp 2.0

//自动转委托

this.MouseMove += Form1_MouseMove;

Label lbl = this.label1; //这个变量下面使用了闭包（简单地说，使用外部的局部变量）

this.MouseMove += new MouseEventHandler(delegate(object sender, MouseEventArgs e) { lbl.Text = e.X + "," + e.Y; });

this.MouseMove += delegate(object sender, MouseEventArgs e) { lbl.Text = e.X + "," + e.Y; };

//csharp 3.0

//使用Lambda表达式

this.MouseMove += (object sender, MouseEventArgs e) => { lbl.Text = e.X + "," + e.Y; };　//Lamda

this.MouseMove += (sender, e) => { lbl.Text = e.X + "," + e.Y; }; //可以省略类型

}

void Form1_MouseMove(object sender, MouseEventArgs e)

{

this.label1.Text = e.X + "," + e.Y;

}

//示例3, 数组排序

class Book

{

public string title;

public double price;

public Book(string title, double price) { this.title=title; this.price=price; }

}

private void button2_Click(object sender, EventArgs e)

{

Random rnd = new Random();

Book [] books = new Book[ 10];

for( int i=0; i<books.Length; i++ ) books[i] = new Book( "Book"+i, rnd.Next(100) );

//csharp 1.0

Array.Sort(books, new MyComparer()); //用一个IComparer

//csharp 2.0

Array.Sort<Book>(books, new Comparison<Book>(delegate(Book book1, Book book2) { return (int)(book1.price - book2.price); })); //使用Comparison委托

Array.Sort<Book>(books, delegate(Book book1, Book book2) { return (int)(book1.price - book2.price); });

//csharp 3.0

Array.Sort<Book>(books, (Book book1, Book book2) => (int)(book1.price - book2.price));

Array.Sort<Book>(books, (book1, book2) => (int)(book1.price - book2.price)); //省略参数类型

//使用Linq

IOrderedEnumerable<Book> result = from book in books orderby book.price select book;

var result2 = from book in books where book.price>=0 orderby book.price select book.title;

foreach (string s in result2) Console.Write(s);

var result3 = books

.Where<Book>(b => b.price>=0)

.OrderBy<Book, double>(b => b.price, Comparer<double>.Default)

.Select<Book,Book>(book => book);

foreach (Book b in result3) Console.Write(b.price+" ");

}

class MyComparer : System.Collections.IComparer

{

public int Compare(object x1, object x2)

{

return (int)(((Book)x1).price - ((Book)x2).price);

}

}

}

}