C# 2.0 除了泛型

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C# 2.0 除了泛型

作者：webabcd

介绍

C# 2.0 除了泛型之外的东东。

可空类型

/*

*可空类型    

*/

using System;

using System.Data;

using System.Configuration;

using System.Collections;

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;

public partial class CSharp20_Nullable : System.Web.UI.Page

{

        protected void Page_Load(object sender, EventArgs e)

        {

                // 针对值类型的可空类型

                Nullable<DateTime> dt = null;

                DateTime? dt2 = null;

                // ??分配默认值

                int? x = null;

                int y = x ?? -1;

                // x的默认值为0

                Response.Write(y.ToString());

        }

}

运行结果

-1

匿名方法

* 匿名方法

public partial class CSharp20_AnonymousMethod : System.Web.UI.Page

                Button btn = new Button();

                btn.Text = "按钮";

                // 一般方法

                btn.Click += new EventHandler(btn_Click);

                // 省略掉委托类型

                btn.Click += btn_Click2;

                // 不带参数的匿名方法

                btn.Click += delegate { Response.Write("按钮被单击（不带参数的匿名方法）<br />"); };

                // 带参数的匿名方法（参数数量和类型要一致）

                btn.Click += delegate(object obj, EventArgs er) { Response.Write("按钮被单击（带参数的匿名方法）<br />"); };

                Page.Form.Controls.Add(btn);

        void btn_Click(object sender, EventArgs e)

                Response.Write("按钮被单击<br />");

        void btn_Click2(object sender, EventArgs e)

                Response.Write("按钮被单击（省略掉委托类型）<br />");

按了按钮后的运行结果

按钮被单击

按钮被单击（省略掉委托类型）

按钮被单击（不带参数的匿名方法）

按钮被单击（带参数的匿名方法）

迭代器

* 迭代器

* 要实现foreach必须实现接口IEnumerable或者IEnumerator

public class Charp20Yield

        public static IEnumerable YieldTest()

                string[] ary = new string[] { "a", "b", "c", "d", "e", "f", "g" };

                foreach (string s in ary)

                {

                        if (s != "e")

                        {

                                // 产生枚举元素

                                yield return s;

                        }

                        else

                                // 中断迭代

                                yield break;

                }

}

public partial class CSharp20_Iterator : System.Web.UI.Page

                // 使用自定义迭代器

                foreach (string s in Charp20Yield.YieldTest())

                        Response.Write(s);

                        Response.Write("<br />");

a

b

c

d

partial类

* partial类

// partial类可以写在不同的文件里，实际上就是取并集，类的修饰符要一致

public partial class PartialTest : IDisposable

        public string Get()

                return "PartialTest";

public partial class PartialTest

        public void Dispose()

                // 略

public partial class CSharp20_Partial : System.Web.UI.Page

                PartialTest pt = new PartialTest();

                Response.Write(pt.Get());

                pt.Dispose();

PartialTest

其它

* 其它

// 指定别名

using xyz = System.Text;

public partial class CSharp20_Other : System.Web.UI.Page

                CSharp20_Other_Test c = new CSharp20_Other_Test();

                c.CurrentTime = DateTime.Now;

                // 下面这句会报错

                // Response.Write(c.CurrentTime.ToLongDateString());

                // 没问题，因为set是internal的

                c[2] = "insert";

                Response.Write(c[2]);

                Response.Write("<br />");

                // 自定义类与framework类 类名重复时，自定义类优先

                // xyz是命名空间别名

                // 访问全局的话用gloab

                Response.Write(xyz::Encoding.Default.EncodingName);

public class CSharp20_Other_Test

        private DateTime _currentTime;

        public DateTime CurrentTime

                // 给访问器增加修饰符

                // 如果接口定义访问器了，则所有继承的都是public

                protected get { return _currentTime; }

                set { _currentTime = value; }

        private string[] ary = new string[] { "a", "b", "c", "d", "e", "f", "g" };

        public string this[int index]

                get { return ary[index]; }

                // 给索引器增加修饰符

                internal set { ary[index] = value; }

insert

简体中文(GB2312)

OK