namespace City
{
    namespace MySchool
    {
        namespace Class
        {
            class Student
            {
                // 此处编写代码
            }
        }
    }

using user = City.MySchool.Class;//定义别名
namespace MySchool
{
    class Student
    {
        user.Student stu = new user.Student();//使用别名
    }
}

class Add
{
    public int Sum(int para1, int para2)
    {…}
    public int Sum(int para1, int para2,int para3)//参数个数不同
    {…}
    public string Sum(string para1, string para2)//参数类型不同
    {…}
}

class Student
{
		public Student() { }
        public Student(string name, int age, string hobby)
        {
                this.Name = name;
                this.Age = age;
                this.Hobby = hobby;
        }
}
//实例化
Student scofield = new Student();
Student zhang =    new Student("张三", 20, "唱歌");

public class Student:Person //通过：+基类名来声明
public class Teacher:Person

public Student(string name, Genders gender, 
       int age, string hobby, int popularity)
{
	//父类属性
    this.Name = name;
    this.Age = age;
    this.Gender = gender;
    //学生类扩展的属性
    this.Hobby = hobby;
    this.Popularity = popularity;
}
public void SayHi()
{
    //学生的SayHi
}
//调用
Student zhang = new Student(…);
zhang.SayHi();

public Student(string name, Genders gender, 
       int age, string hobby, int popularity)
: base(name,age,gender)  //调用父类的构造函数
{
    //学生类扩展的属性
    this.Hobby = hobby;
    this.Popularity = popularity;
}

abstract class Person	//基类
{
       public abstract void SayHi();
}
//……
Person person = new Person(); //编译错误,不能实例化
//……	派生类
public override void SayHi()//然后在派生类override重载方法
{		
       //…具体实现内容
}

//Person类中默认实现通用的SayHi()
public virtual void SayHi()
{
       //…省略具体实现
}

class Circle:Shape
{
	//……
	public sealed override void Draw()
	{
		//……
	}
}

 interface Drawable{	//定义一个接口
   Void draw();
}
//在Circle类实现Drawable接口，即实现接口中声明的所有方法。
class Circle : Drawable{
	Public void Draw(){
  	.....
	}
}

public class Student:Person,IComparable	//实现该接口
{
        public int CompareTo(object obj)	//实现CompareTo  
        {
               if (!(obj is Student))
                  throw new Exception("只能与Student 对象比较");
          
               Student other = obj as Student;	//按姓名升序
               return this.Name.CompareTo(other.Name);
        }
}

public enum Test
{ 
       S1 ,S2,Y2
}
Console.WriteLine("S2的值是{0}.", Test.S2.ToString());//枚举转换为字符串
(Test)(Enum.Parse(typeof(Accp),"S2");//字符串转换为枚举

访问修饰符 struct 结构名
{ 
       定义结构成员
}
//比如
public struct StructStudent
{
       public string Name;
       public int Age;
       public string Hobby;
       public int Popularity;
       public void SayHi()
       {
          // ….
       }
}
//调用
 StructStudent myStu;//不能用new
 myStu.Age = 20;//赋值结构成员
 myStu.Gender = Genders.Female;
 myStu.Hobby = "唱歌";
 myStu.Name = "张三";
 myStu.Popularity = 100;
 myStu.SayHi();

//初始化
using System.Collections;	//引入命名空间
//定义
ArrayList students = new ArrayList();	//实例化一个对象
ArrayList Teachers = new ArrayList(5);	//可以指定长度

//添加
Student scofield = new Student("Scofield", Genders.Male, 25, "唱歌");
students.Add(scofield);	//调用add()

//访问：(类型) ArrayList[index]  //按指定索引（下标）取得对象
Student stu1 = (Student)students[0];//从0开始,注意类型转换
stu1.SayHi();

//删除
//ArrayList.Remove(对象名) //删除指定对象名的对象
//ArrayList.RemoveAt(index) //删除指定索引的对象
//ArrayList.Clear() //清除集合内的所有元素
students.RemoveAt(0);	//通过索引删除对象
students.Remove(zhang);	//指定删除对象
Student leave = (Student)students[0];//取得删除后第一个对象
leave.SayHi();	//删除后的索引会自动调整

//遍历
for (int i = 0; i < students.Count; i++)
{
       Student stuFor = (Student)students[i];
       Console.WriteLine(stuFor.Name);
}
foreach (Object stuo in students)
{
    Student stuForeach = (Student)stuo;
    Console.WriteLine(stuForeach.Name);
}

//添加
students.Add(scofield.Name,scofield);	//(key,value)
//访问
Student stu2 = (Student)students[“张三"];//通过key获取元素(注意类型转换)
stu2.SayHi();
//删除
students.Remove(“张三");	//通过key删除元素
//遍历
foreach (Object stuo in students.Values)
{			//不能遍历整个对象，而是遍历Values
       Student stu = (Student)stuo;
       Console.WriteLine(stu.Name);
}
foreach (string name in students.Keys)
{			//可以遍历keys
       Console.WriteLine(name);
}

using System.Collections.Generic	//命名空间
//定义
List<Student> students = new List<Student>();//只能保存student对象
//添加
Student scofield = new Student("Scofield", Genders.Male, 25, "唱歌");
students.Add(scofield);
Teacher jacky = new Teacher(“王五", 4);
students.Add(jacky );	//报错
//访问
Student stu1 = students[2];	//使用索引访问，无需类型转换
stu1.SayHi();
//删除
Students.RemoveAt(0);	//利用索引删除
//遍历
foreach (Student stu in students)
{				//无需类型转换
       Console.WriteLine(stu.Name);
}

//定义
//Key存储string类型，Value存储Student类型
Dictionary<string,Student> students = new Dictionary<string,Student>();
//添加
students.Add(scofield.Name, scofield);
students.Add(jacky.Name,jacky);//teacher报错
//访问
Student stu2 = students[“张三"];
//删除
students.Remove(“张三");
//遍历
foreach (Student student in students.Values)
{
       Console.WriteLine(student.Name);
}

using System.Runtime.Serialization.Formatters.Binary;

public FileStream(string path,FileMode mpde)
public FileStream(string path,FileMode mpde,FileAccess access)
public FileStream(string path,FileMode mpde,FileAccess access,FileShare share)

FileStream myfs = new FileStream( 'D:',  FileMode.Create);	//创建文件流

StreamWriter mySw = new StreamWriter(myfs);	//创建写入器
mySw.Write(content);	//写入方法
//mySw.WriteLine(content);	//写入一行数据
mySw.Close();	//关闭写入器

StreamReader mySr = new StreamReader(myfs);	//创建读取器
content = mySr.ReadToEnd();	//读取到文件末尾
//content = mySr.ReadLine();	//读取一行
mySr.Close();	//关闭读取器

XmlDocument myXml = new XmlDocument();
myXml.Load("Student.xml");	//读取xml文件

XmlNode student = myXml.DocumentElement;	//获取根节点

foreach (XmlNode node in student.ChildNodes )	//获取当前节点所有子节点
{
        switch (node.Name)	//当前节点名字
        {
                    case "Name":
                        Console.WriteLine("姓名:{0}",node.InnerText);//当前节点值
                        break; 
                        // …
        }
}

public override bool FillArticles()
        {
            string filePath = "rss.temp";
            if (this.Articles == null)
                this.Articles = new Dictionary<string, Article>();
            try
            {
                WebClient webClient = new WebClient();     //WebClient类下载文件
                webClient.DownloadFile(this.Url, filePath);//download方法 把地址中的文件下载到 filePath
                XmlDocument xmlDoc = new XmlDocument();
                xmlDoc.Load(filePath); //采用XmlDocument类的Load方法加载
                XmlNode channel = xmlDoc.DocumentElement.FirstChild; //XmlDocument的根元素：DocumentElement 第一个子结点：FirstChild
                foreach (XmlNode node in channel.ChildNodes) //XmlNote类型的子结点
                {
                   
                    if (node.Name == "item") //结点名称若是item
                    {
                        Article arc = new Article();
                        foreach (XmlNode childNode in node.ChildNodes)
                        {

                            if (childNode.Name == "title")
                                arc.Title = childNode.InnerText; //innerText表示结点的值
                            if (childNode.Name == "link")
                                arc.Url = childNode.InnerText;
                        }
                        this.Articles.Add(arc.Title,arc); //添加到Articles（Dictionary）
                    }               
                }
                this.Clicks++; //浏览一次 +1
                return true;

            }
            catch (Exception ex) //download过程可能出错 捕获异常
            {
                Console.WriteLine(ex.ToString());
                return false;
            }
        }

public Pen(Color color);	//创建某一颜色的Pen对象
public Pen(Color color，float width);	//创建Pen并设置画笔宽度和颜色
public Pen(Brush brush);	//创建某一刷子样式的Pen
public Pen(Brush,float width);	//创建某一刷子样式的Pen并设置相应宽度

SolidBrush 刷子=new SolidBrush(颜色)
SolidBrush reBrush=new SolidBrush(Color.Blue);

HatchBrush 刷子=new HatchBrush(style,foreColor,bakcColor)
HatchBrush HB=new HatchBrush(Hatch.Cross,Color.Cyan,Color.Chocolate);

Image img;
img=Image.FormFile(@"路径图形文件名.bmp");
TextureBrush txtBrush=new TextureBrush(img,style);

LinearGradientBrush 刷子 =new LinearGradientBrush(point1,point2,point3,point4)

private void Form1_MouseDown(object sebder,MouseEventArgs e)
{
	//……
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace FormPaintDemo
{
    public partial class Form1 : Form
    {
        private bool mark = false;//表示鼠标左键是否按下，如按下鼠标再移动将画曲线
        private Point point;//记录画下一条很短线段的起始点。
        private List<Point> Point_List;    //用来记录1条曲线的所有点。
        private List<List<Point>> Line_List;

        Pen pen1 = new Pen(Color.Red, (float)3.0);
        Graphics g;

        public Form1()
        {
            InitializeComponent();
            Line_List = new List<List<Point>>();
            g = this.CreateGraphics();
            
        }

        private void Form1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)  
            {
                Point_List = new List<Point>();  //建立数组，记录1条曲线的所有点
                point.X = e.X;
                point.Y = e.Y;
                mark = true;
                Point_List.Add(point);      //记录曲线起点的坐标
            }

        }

        private void Form1_MouseMove(object sender, MouseEventArgs e)
        {
            if (mark)
            {
               
                g.DrawLine(pen1, point.X, point.Y, e.X, e.Y);
                point.X = e.X;
                point.Y = e.Y;
                Point_List.Add(point);     //记录曲线中其它点的坐标
            }

        }

        private void Form1_MouseUp(object sender, MouseEventArgs e)
        {
            mark = false;
            Line_List.Add(Point_List);

        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Point p1, p2;
            foreach (List<Point> pl in Line_List)//取出每条线
            {
                for (int k = 0; k < pl.Count - 1; k++)//重画每条线的点
                {
                    p1 = pl[k];
                    p2 = pl[k + 1];
                    g.DrawLine(pen1, p1, p2);
                }
            }

        }
    }
}

using System;
using System.Data;
using System.Data.SqlClient;
namespace CommadnDemo
{
	class Class1
	{
		[STAThread]
		static void Main(string[] args)
		{
			//创建一个Connection对象来连接数据库
			//连接数据库服务器名：jmucj；数据库：northwind；用户名：sa；密码：123
			SqlConnection cn =new SqlConnection("server=jmucj;database=northwind;uid=sa;pwd=123");
			SqlCommand cmd=new SqlCommand();//创建Command对象来操作数据库
			cmd.Connection=cn;
			cn.Open();//打开连接
			cmd.CommandType=CommandType.StoredProcedure;//调用存储过程
           
			cmd.CommandText="getproductlist";//存储过程名
			cmd.Parameters.Add(new SqlParameter("@id",SqlDbType.Int,4));//传参@id=4，整型
            cmd.Parameters["@id"].Direction = ParameterDirection.Input;//输入参数
			int id=int.Parse(Console.ReadLine());//从控制台读取id
			cmd.Parameters["@id"].Value=id;//赋值
			SqlDataReader reader=cmd.ExecuteReader();//创建Reader对象来读取
			while(reader.Read())	//遍历打印读取结果(第一列的字符串和第三列的32位整型)
			{
				Console.WriteLine(reader.GetString(1)+"    "+reader.GetInt32(3).ToString());
			}
			cn.Close();//关闭连接
			Console.ReadLine();
		}
	}
}

private void button2_Click(object sender, System.EventArgs e)
		{	//监听点击事件
			DataSet dstemp=new DataSet();
			try 
			{	//获取表自上次调用AcceptChanges以来的所发生的所有更改
				dstemp=ds.GetChanges(DataRowState.Modified);
				da.Update(dstemp);	//更新数据源中数据，同步更改
				ds.Merge(dstemp);	//合并两个DataSet对象，同步数据
				ds.AcceptChanges();
			}
			catch(Exception ex) 	//捕获异常
			{
				if(ds.HasErrors)	//弹框显示所有异常所在的行列名
				{
					foreach(DataTable table in ds.Tables)
					{
						if(table.HasErrors)
						{
							foreach(DataRow row in table.Rows)
							{
								if(row.HasErrors)
								{
									MessageBox.Show("Row: " + row["CustomerID"],
										row.RowError);

									foreach(DataColumn col in row.GetColumnsInError())
									{
										MessageBox.Show(col.ColumnName, 
											"Error in this column");
									}
									row.ClearErrors(); //清除数据
									row.RejectChanges(); //拒绝更新
								}
							}
						}
					}
				}
				MessageBox.Show(ex.Message);	//弹框显示异常信息
			} 
		}

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
namespace DataRelationCS01
{
    class Program
    {
        static void Main(string[] args)
        {
            DataSet ds = new DataSet();
            
            DataColumn col;
            DataTable dt = new DataTable("Customers");//新建Customers表
            ds.Tables.Add(dt);//添加到内存数据源
            col = ds.Tables["Customers"].Columns.Add("CustomerID", typeof(string));
            col.MaxLength = 5;  //设置一列值为CustomerID，字符串类型，最大长度为5
            col = ds.Tables["Customers"].Columns.Add("CompanyName", typeof(string));
            col.MaxLength = 40; //设置一列值为CompanyName，字符串类型，最大长度为40
            col = ds.Tables["Customers"].Columns.Add("ContactName", typeof(string));
            col.MaxLength = 30; //设置一列值为ContactName，字符串类型，最大长度为30
            col = ds.Tables["Customers"].Columns.Add("Phone", typeof(string));
            col.MaxLength = 24; //设置一列值为Phone，字符串类型，最大长度为30
            ds.Tables["Customers"].PrimaryKey = new DataColumn[] {ds.Tables["Customers"].Columns["CustomerID"]};
            //设置Customers表主键为CustomerID
            DataRow row;
            row = ds.Tables["Customers"].NewRow();//新建一行并赋值
            row[0] = "a0";
            row[1] = "IBM";
            row[2] = "Michael";
            row[3] = "1234";
            ds.Tables["Customers"].Rows.Add(row);
            row = ds.Tables["Customers"].NewRow();
            row[0] = "b0";
            row[1] = "DELL";
            row[2] = "David";
            row[3] = "4567";
            ds.Tables["Customers"].Rows.Add(row);

            dt = new DataTable("Orders");//又新建一个Orders表，大同小异
            ds.Tables.Add(dt);
            col = ds.Tables["Orders"].Columns.Add("OrderID", typeof(int));
            col.AutoIncrement = true;   //设置自增长
            col.AutoIncrementSeed = 1;
            col.AutoIncrementStep = 1;
            col.ReadOnly = true;    //设置只读
            col = ds.Tables["Orders"].Columns.Add("CustomerID", typeof(string));
            col.AllowDBNull = false;    //不允许为空
            col.MaxLength = 5;
            ds.Tables["Orders"].Columns.Add("EmployeeID", typeof(int));
            ds.Tables["Orders"].Columns.Add("OrderDate", typeof(DateTime));
            ds.Tables["Orders"].PrimaryKey = new DataColumn[] {ds.Tables["Orders"].Columns["OrderID"]};

            row = ds.Tables["Orders"].NewRow();
            row[1] = "a0";
            row[2] = 3;
            DateTime mydatetime;
            mydatetime = new DateTime(2005, 1, 8);
            row[3] = mydatetime;
            ds.Tables["Orders"].Rows.Add(row);

            row = ds.Tables["Orders"].NewRow();
            row[1] = "b0";
            row[2] = 4;
            mydatetime = new DateTime(2005, 4, 13);
            row[3] = mydatetime;
            ds.Tables["Orders"].Rows.Add(row);

            DataRelation rel;
            
            rel = new DataRelation("CustomersOrders",   //把两个表通过CustomerID联系起来
                ds.Tables["Customers"].Columns["CustomerID"], 
                ds.Tables["Orders"].Columns["CustomerID"]);
            ds.Relations.Add(rel);

        
            Console.WriteLine(ds.Relations.Count);  //联系的数量(1)
            Console.WriteLine(ds.Relations[0].RelationName);//第一个联系的名字(CustomersOrders)
            Console.WriteLine(ds.Tables.Count);//表的数量(2)
            Console.WriteLine(ds.Tables[0].PrimaryKey.Length);//第一个表的主键长度(1)
            Console.WriteLine(ds.Tables[0].Constraints.Count);//第一个表的约束的数量(1)
            Console.WriteLine(ds.Tables[0].Columns.Count);//第一个表列数(4)

            //select CustomerID,CompanyName,OrderID,OrderDate where Customers.CustomerID=Orders.CustomerID
            foreach (DataRow dr1 in ds.Tables["Customers"].Rows)
            {
                Console.Write(dr1["CustomerID"] + "--" + dr1["CompanyName"]);
                foreach (DataRow dr2 in dr1.GetChildRows("CustomersOrders"))
                    Console.WriteLine("   " + dr2["OrderID"] + "    " + dr2["OrderDate"]);
            }


            Console.WriteLine("----******************************************----");

            foreach (DataRow dr2 in ds.Tables["Orders"].Rows)
            {
                Console.Write(dr2["OrderID"] + "  " + dr2["OrderDate"]);
                DataRow dr1 = dr2.GetParentRow(rel);
                Console.WriteLine("   " + dr1["CustomerID"] + "-" + dr1["CompanyName"]);
            }

            ds.WriteXml(@"C:a.xml");// 写入xml
            DataSet newds = new DataSet();
            newds.ReadXml(@"C:a.xml");//读取该xml
            Console.WriteLine("*********************");
            Console.WriteLine("*********************");
            Console.WriteLine("*********************");
            Console.WriteLine(newds.Tables.Count);//表的数量(运行结果与前面一致)
            Console.WriteLine(newds.Tables[0].Rows.Count);//第一个表的行数

            Console.WriteLine(newds.Tables[0].Columns.Count);//第一个表的列数

            Console.ReadLine();

        }
    }
}

using System;
using System.Data;
using System.Data.SqlClient;

namespace DataAdapterDemo03
{
	class Class1
	{
		
		[STAThread]
		static void Main(string[] args)
		{
			//连接数据库：本地服务器；数据库名：northwind；集成安全用Windows身份验证
			SqlConnection cn =new SqlConnection("server=localhost;database=northwind;integrated security=sspi");
			
			SqlDataAdapter da1=new SqlDataAdapter();//新建DataAdapter对象
			SqlCommand selectcmd1=new SqlCommand("select * from category",cn);//新建查询语句
			da1.SelectCommand=selectcmd1;//加到DataAdapter的SelectCommand对象


			SqlCommand selectcmd2=new SqlCommand();//同上
			 selectcmd2.Connection=cn;
			 selectcmd2.CommandType=CommandType.Text;
             selectcmd2.CommandText = "select * from products";
			 SqlDataAdapter da2=new SqlDataAdapter(selectcmd2);

			 DataSet ds=new DataSet();//新建DataSet对象
            cn.Open();//开启连接
			 da1.Fill(ds,"category");//添加刷新category表的行，并加入到ds中
			da2.Fill(ds, "products");
            cn.Close();//关闭连接
            Console.WriteLine("Table Count: "+ds.Tables.Count.ToString());//输出ds中表的数量
			while (true)
			{
				Console.WriteLine("请选择输入1--2");
				string i=Console.ReadLine();
				if (i=="1")//如果控制台输入1
				{
					foreach(DataRow dr in ds.Tables["category"].Rows)//打印category表所有信息
					{
						int j=0;
						for (j=0;j<ds.Tables["category"].Columns.Count-1;j++)
						{
							Console.Write(dr[j].ToString()+" "+"||");
						}
						Console.WriteLine();
					}
				}
				else if(i=="2")//如果控制台输入2
				{
					foreach(DataRow dr in ds.Tables["products"].Rows)//打印products表所有信息
					{
						int j=0;
						for (j=0;j<ds.Tables["products"].Columns.Count-1;j++)
						{
							Console.Write(dr[j].ToString()+" "+"||");
						}
						Console.WriteLine();
					}
				}
					 
			}
			Console.ReadLine();
		}
	}
}