枚举类型,新手型的,高人勿近！

搞了个枚举,枚举类型定义了一组符号和数值对,每个枚举类型都直接继承于system.enum.而system.enum又继承于system.valuetype,因此枚举类型是值类型,枚举类型week 定义了一个星期7天.

 1using System;
 2using System.Data;
 3using System.Configuration;
 4using System.Web;
 5using System.Web.Security;
 6using System.Web.UI;
 7using System.Web.UI.WebControls;
 8using System.Web.UI.WebControls.WebParts;
 9using System.Web.UI.HtmlControls;
10
11public partial class _Default : System.Web.UI.Page 
12{
13    protected void Page_Load(object sender, EventArgs e)
14    {
15        if (!IsPostBack)
16        {
17            TestEnum();
18            Week weekDay = (Week)100;
19            ValiateEnum(weekDay);
20            Response.End();
21        }
22
23    }
24
25//定义星期的枚举
26    public enum Week
27    {
28        Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday
29    }
30    private void TestEnum()
31    {
32        Week[] weekList = (Week[])Enum.GetValues(typeof(Week));
33        foreach (Week w in weekList)
34        {
35            Response.Write(w.ToString("D") + "\t" + w.ToString("G") + "<br>");
36        }
37        string[] nameList = Enum.GetNames(typeof(Week));
38        foreach (string s in nameList)
39        { Response.Write(s + "<br>"); }
40        Response.Write(Enum.GetName(typeof(Week),3)+"<br>");
41        Response.Write(Enum.GetName(typeof(Week),Week.Wednesday)+ "<br>");
42        //Response.Write("Base class is "+Enum.GetUnderlyingType(typeof(Week)+"<br>"));
43        //不知道错哪了,不注释掉不让调试.
44    }
45    private void ValiateEnum(Week w)
46    {
47        if (Enum.IsDefined(typeof(Week), w) == false)
48        {
49            Response.Write(w.ToString() + "Is not exist.<br>");
50        }
51        else
52        {
53            Response.Write(w.ToString() + "\t Is exist.<br>");
54        }
55    }
56}
57
58

问题就出现了,其中有个GetValue和 GetValues,虽然就多了一个S ,但区别很大的.
还有一个GetName和 GetNames,也不一样,GetName是指定枚举中检索具有指定值的常数的名称;
GetNames是指检索指定枚举中常数名称的数组;
还有上面　Response.Write(w.ToString("D") + "\t" + w.ToString("G") + "<br>");里面的Ｄ和Ｇ是什么意思？