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步步为营VS 2008 + .NET 3.5(3) - C# 3.0新特性之Automatic Properties（自动属性）、Object Initializers（对象初始化器）、Collection Initializers（集合初始化器）和Extension Methods（扩展方法）


作者：webabcd


介绍
·Automatic Properties（自动属性）
·Object Initializers（对象初始化器）
·Collection Initializers（集合初始化器）
·Extension Methods（扩展方法）


示例
AutomaticProperties.cs（自动属性）
using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml.Linq;

/**////
/// AutomaticProperties（自动属性）的摘要说明
///
public class AutomaticProperties
{
public int ID { get; set; }

// 上面的ID属性（自动属性）等同于下面的ID属性

// private int _id;
// public int ID
// {
// get { return _id; }
// set { _id = value; }
// }
}

using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml.Linq;

/**////
/// ObjectInitializers（对象初始化器）的摘要说明
///
public class ObjectInitializers
{
public int ID { get; set; }
public string Name { get; set; }

public void ObjectInitializersTest()
{
ObjectInitializers oi = new ObjectInitializers { ID = 1, Name = "webabcd" };

// 上面的oi对象（对象初始化器）等同于下面的oi对象

// ObjectInitializers oi = new ObjectInitializers();
// oi.ID = 1;
// oi.Name = "webabcd";
}
}

using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml.Linq;

using System.Collections.Generic;

/**////
/// CollectionInitializers（集合初始化器）的摘要说明
///
public class CollectionInitializers
{
public int ID { get; set; }
public string Name { get; set; }

public void CollectionInitializersTest()
{
List list = new List
{
new CollectionInitializers { ID = 1, Name = "webabcd" },
new CollectionInitializers { ID = 2, Name = "webabcdefg" },
new CollectionInitializers { ID = 3, Name = "webabcdefghijklmn" }
};

// 上面的list集合（集合初始化器）等同于下面的list集合

// List list = new List();
// list.Add(new CollectionInitializers { ID = 1, Name = "webabcd" });
// list.Add(new CollectionInitializers { ID = 2, Name = "webabcdefg" });
// list.Add(new CollectionInitializers { ID = 3, Name = "webabcdefghijklmn" });
}
}

using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml.Linq;

/**////
/// ExtensionMethods 的摘要说明
///
public class ExtensionMethods
{
public void ExtensionMethodsTest()
{
string s = "123";
// 使用string的ToInt32()扩展方法
int i = s.ToInt32();
// i == 123

string[] ary = new string[] { "a", "b", "c" };
// 使用object的In()扩展方法
bool b = "b".In(ary);
// b == true
}
}

/**////
/// 扩展方法（类和方法均为static）
/// 使用的时候要引用该类的命名空间
///
public static class MyExtensionMethods
{
// this代表扩展方法应用于string类型上
// ToInt32()是将string类型转换为int类型的扩展方法
public static int ToInt32(this string s)
{
int i;
Int32.TryParse(s, out i);

return i;
}

// this代表扩展方法应用于object类型上
// 该扩展方法需要一个类型为System.Collections.IEnumerable的参数
// In()是判断一个object是否存在于一个System.Collections.IEnumerable中的扩展方法
public static bool In(this object o, System.Collections.IEnumerable e)
{
foreach (object i in e)
{
if (i.Equals(o))
{
return true;
}
}

return false;
}
}