C# Dictionary学习

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Collections.Generic;
public partial class test : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Dictionary<string, int> dict = new Dictionary<string, int>();
        DataTable dt = GetDataTable();
        if (dt != null && dt.Rows.Count > 0)
        {
            foreach (DataRow dr in dt.Rows)
            {
                if (!dict.ContainsKey(dr[0].ToString()))
                    dict.Add(dr[0].ToString(), Int32.Parse(dr[1].ToString()));
                //而使用索引器来赋值时，如果键已经存在，就会修改已有的键的键值
                //    dict[dr[0].ToString()] = Int32.Parse(dr[1].ToString());              
 }
        }
        //泛型结构体
 foreach (KeyValuePair<string, int> kvp in dict)
            Response.Write("key=" + kvp.Key + ",value=" + kvp.Value + "<br />");
     
        //输出结果：
        //            key=新闻,value=3
        //            key=产品,value=8
        //===================================================//
 Dictionary<int, Person> pdict = new Dictionary<int, Person>();
        for (int i = 1; i < 3; i++)
        {
            Person p = new Person();
            p.Id = i;
            p.Name = "名称 " + i;
            pdict.Add(i, p);
        }
        //获取值得集合
 foreach (Person p in pdict.Values)
        {
            Response.Write("id=" + p.Id + ",name=" + p.Name + "<br />");
        }
        //输出结果：
        //            id=1,name=名称 1
        //            id=2,name=名称 2
 }
    DataTable GetDataTable()
    {
        DataTable dt = new DataTable();
        DataRow dr;
        dt.Columns.Add(new DataColumn("Type", typeof(string)));
        dt.Columns.Add(new DataColumn("Amount", typeof(Int32)));
        dr = dt.NewRow();
        dr[0] = "新闻";
        dr[1] = "3";
        dt.Rows.Add(dr);      
        dr = dt.NewRow();
        dr[0] = "产品";
        dr[1] = "8";
        dt.Rows.Add(dr);
        dr = dt.NewRow();
        dr[0] = "产品";
        dr[1] = "8";
        dt.Rows.Add(dr); 
        return dt;
    }
    public class Person
    {
        public int Id { get; set; }
        public string Name { get; set; }
    }

/*
//C#3.0 Dictionary初始化赋值的新语法

  Dictionary<int, string> dic = new Dictionary<int, string>{
      {1,"A"}, {2,"B"}, {3,"C"}, {4,"D"},{5,"E"},
      {6,"F"}, {7,"G"}, {8,"H"},{9,"I"},{10,"J"},
      {11,"K"},{12,"L"},{13,"M"},{14,"N"},{15,"O"},
      {16,"P"},{17,"Q"},{18,"R"},{19,"S"},{20,"T"},
      {21,"U"}, {22,"V"},{23,"W"}, {24,"X"},{25,"Y"},
      {26,"Z"}
  };
string val = dict.FirstOrDefault(d => d.Key == 2).Value; 

*/ 


}