using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Data;

namespace ConsoleApplication1

{

class Program

{

static void Main(string[] args)

{

#region 1、typeof()与GetType()的区别

if (false)

{

string name = "lxf";

string str1 = name.GetType().Name; // String

int a = 123;

string str2 = typeof(int).Name; //Int32

string str3 = a.GetType().Name; //Int32

}

#endregion

#region 2、DataTable的select参数 string filterExpression熟悉

if (false)

{

DataTable dt = new DataTable("Student");

DataColumn dc1 = new DataColumn("ID", typeof(int));

DataColumn dc2 = new DataColumn("Name", typeof(string));

DataColumn dc3 = new DataColumn("Birthday", typeof(DateTime));

dt.Columns.Add(dc1);

dt.Columns.Add(dc2);

dt.Columns.Add(dc3);

DataRow dr1 = dt.NewRow();

dr1["ID"] = 12;

dr1["Name"] = "lxf";

dr1["Birthday"] = new DateTime(1991, 11, 17);

DataRow dr2 = dt.NewRow();

dr2["ID"] = 5;

dr2["Name"] = "zhangsan";

dr2["Birthday"] = new DateTime(1990, 05, 17);

dt.Rows.Add(dr1);

dt.Rows.Add(dr2);

DataRow[] drs = dt.Select("Birthday='1990.05.17'");

foreach (var item in drs)

{

Console.WriteLine("姓名：" + item["Name"] + "年龄：" + item["Birthday"]);

}

}

#endregion

#region 3、字典和集合值的获取 键|索引

if (false)

{

Dictionary<string, string> dic = new Dictionary<string, string>();

dic["name"] = "lxf"; // 字典只能根据键获取值 不能根据索引获取值 业务它是无需的

dic["sex"] = "male";

foreach (var item in dic)

{

Console.WriteLine(item);

}

List<string> list = new List<string>(); // 只能通过索引访问集合元素，访问前必须先赋值，不然会报超出索引范围异常

list.Add("李小飞");

list.Add("马云");

list[0] = "ls"; //

list[1] = "my";

foreach (var item in list)

{

Console.WriteLine(item);

}

}

// DataRow对象既可以用索引访问列值 也可用列名访问列值

#endregion

#region StringBuilder测试

StringBuilder sb = new StringBuilder();

sb.Append("acadf{0}kljl"); //不会当做占位符

sb.AppendFormat("1243{0}23452", "中国"); //acadf{0}kljl1243中国23452

Console.WriteLine(sb.ToString());

Console.WriteLine("===============");

string str = sb.ToString();

sb.AppendFormat(str, "哈哈");

Console.WriteLine(sb.ToString()); //acadf{0}kljl1243中国23452acadf哈哈kljl1243中国23452

#endregion

Console.ReadKey();

}

}

}