原帖：http://wz.csdn.net/url/1213077/

一、从控制台读取东西代码片断：
using System;

class TestReadConsole
{
public static void Main()
{
Console.Write(Enter your name:);
string strName = Console.ReadLine();
Console.WriteLine( Hi + strName);
}
}

二、读文件代码片断：
using System;
using System.IO;

public class TestReadFile
{
public static void Main(String[] args)
{
// Read text file C: emp est.txt
FileStream fs = new FileStream(@c: emp est.txt , FileMode.Open, FileAccess.Read);
StreamReader sr = new StreamReader(fs);

String line=sr.ReadLine();
while (line!=null)
{
Console.WriteLine(line);
line=sr.ReadLine();
}

sr.Close();
fs.Close();
}
}

三、写文件代码：
using System;
using System.IO;

public class TestWriteFile
{
public static void Main(String[] args)
{
// Create a text file C: emp est.txt
FileStream fs = new FileStream(@c: emp est.txt , FileMode.OpenOrCreate, FileAccess.Write);
StreamWriter sw = new StreamWriter(fs);
// Write to the file using StreamWriter class
sw.BaseStream.Seek(0, SeekOrigin.End);
sw.WriteLine( First Line );
sw.WriteLine( Second Line);
sw.Flush();
}
}

四、拷贝文件：
using System;
using System.IO;

class TestCopyFile
{
public static void Main()
{
File.Copy(c:\temp\source.txt, C:\temp\dest.txt );
}
}

五、移动文件：
using System;
using System.IO;

class TestMoveFile
{
public static void Main()
{
File.Move(c:\temp\abc.txt, C:\temp\def.txt );
}
}

六、使用计时器：
using System;
using System.Timers;

class TestTimer
{
public static void Main()
{
Timer timer = new Timer();

timer.Elapsed += new ElapsedEventHandler( DisplayTimeEvent );
timer.Interval = 1000;
timer.Start();
timer.Enabled = true;

while ( Console.Read() != \’\’q\’\’ )
{
//————-
}
}
public static void DisplayTimeEvent( object source, ElapsedEventArgs e )
{
Console.Write( {0}, DateTime.Now);
}
}

七、调用外部程序：
class Test
{
static void Main(string[] args)
{
System.Diagnostics.Process.Start(notepad.exe);
}
}

ADO.NET方面的：
八、连接Access数据库：
using System;
using System.Data;
using System.Data.OleDb;

class TestADO
{
static void Main(string[] args)
{
string strDSN = Provider=Microsoft.Jet.OLEDB.4.0;Data Source=c:\test.mdb;
string strSQL = SELECT * FROM employees ;

OleDbConnection conn = new OleDbConnection(strDSN);
OleDbCommand cmd = new OleDbCommand( strSQL, conn );
OleDbDataReader reader = null;
try
{
conn.Open();
reader = cmd.ExecuteReader();
while (reader.Read() )
{
Console.WriteLine(First Name:{0}, Last Name:{1}, reader[FirstName], reader[LastName]);
}
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
finally
{
conn.Close();
}
}
}

九、连接SQL Server数据库：
using System;
using System.Data.SqlClient;

public class TestADO
{
public static void Main()
{
SqlConnection conn = new SqlConnection(Data Source=localhost; Integrated Security=SSPI; Initial Catalog=pubs);

SqlCommand cmd = new SqlCommand(SELECT * FROM employees, conn);
try
{
conn.Open();

SqlDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
Console.WriteLine(First Name: {0}, Last Name: {1}, reader.GetString(0), reader.GetString(1));
}

reader.Close();
conn.Close();
}
catch(Exception e)
{
Console.WriteLine(Exception Occured –>> {0},e);
}
}
}

十、从SQL内读数据到XML：
using System;
using System.Data;
using System.Xml;
using System.Data.SqlClient;
using System.IO;

public class TestWriteXML
{
public static void Main()
{

String strFileName=c:/temp/output.xml;

SqlConnection conn = new SqlConnection(server=localhost;uid=sa;pwd=;database=db);

String strSql = SELECT FirstName, LastName FROM employees;

SqlDataAdapter adapter = new SqlDataAdapter();

adapter.SelectCommand = new SqlCommand(strSql,conn);

// Build the DataSet
DataSet ds = new DataSet();

adapter.Fill(ds, employees);

// Get a FileStream object
FileStream fs = new FileStream(strFileName,FileMode.OpenOrCreate,FileAccess.Write);

// Apply the WriteXml method to write an XML document
ds.WriteXml(fs);

fs.Close();

}
}

十一、用ADO添加数据到数据库中：
using System;
using System.Data;
using System.Data.OleDb;

class TestADO
{
static void Main(string[] args)

{
string strDSN = Provider=Microsoft.Jet.OLEDB.4.0;DataSource=c: est.mdb;
string strSQL = INSERT INTO Employee(FirstName, LastName) VALUES(\’\’FirstName\’\’, \’\’LastName\’\’) ;

// create Objects of ADOConnection and ADOCommand
OleDbConnection conn = new OleDbConnection(strDSN);
OleDbCommand cmd = new OleDbCommand( strSQL, conn );
try
{
conn.Open();
cmd.ExecuteNonQuery();
}
catch (Exception e)
{
Console.WriteLine(Oooops. I did it again: {0}, e.Message);
}
finally
{
conn.Close();
}
}
}

十 二、使用OLEConn连接数据库：
using System;
using System.Data;
using System.Data.OleDb;

class TestADO
{
static void Main(string[] args)
{
string strDSN = Provider=Microsoft.Jet.OLEDB.4.0;DataSource=c: est.mdb;
string strSQL = SELECT * FROM employee ;

OleDbConnection conn = new OleDbConnection(strDSN);
OleDbDataAdapter cmd = new OleDbDataAdapter( strSQL, conn );

conn.Open();
DataSet ds = new DataSet();
cmd.Fill( ds, employee );
DataTable dt = ds.Tables[0];

foreach( DataRow dr in dt.Rows )
{
Console.WriteLine(First name: + dr[FirstName].ToString() + Last name: + dr[LastName].ToString());
}
conn.Close();
}
}
十三、读取表的属性：

using System;
using System.Data;
using System.Data.OleDb;

class TestADO
{
static void Main(string[] args)
{
string strDSN = Provider=Microsoft.Jet.OLEDB.4.0;DataSource=c: est.mdb;
string strSQL = SELECT * FROM employee ;

OleDbConnection conn = new OleDbConnection(strDSN);
OleDbDataAdapter cmd = new OleDbDataAdapter( strSQL, conn );

conn.Open();
DataSet ds = new DataSet();
cmd.Fill( ds, employee );
DataTable dt = ds.Tables[0];

Console.WriteLine(Field Name DataType Unique AutoIncrement AllowNull);
Console.WriteLine(==================================================================);
foreach( DataColumn dc in dt.Columns )
{
Console.WriteLine(dc.ColumnName+ , +dc.DataType + ,+dc.Unique + ,+dc.AutoIncrement+ ,+dc.AllowDBNull );
}
conn.Close();
}
}

ASP.NET方面的
十四、一个ASP.NET程序：

void Button1_Click(Object sender, EventArgs e)
{
Label1.Text=TextBox1.Text;
}

Enter your name:

WinForm开发：
十五、一个简单的WinForm程序：
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

public class SimpleForm : System.Windows.Forms.Form
{

private System.ComponentModel.Container components = null;
private System.Windows.Forms.Button button1;
private System.Windows.Forms.TextBox textBox1;
public SimpleForm()
{
InitializeComponent();
}

protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}

#region Windows Form Designer generated code
private void InitializeComponent()
{

this.components = new System.ComponentModel.Container();
this.Size = new System.Drawing.Size(300,300);
this.Text = Form1;

this.button1 = new System.Windows.Forms.Button();
this.textBox1 = new System.Windows.Forms.TextBox();
this.SuspendLayout();

//
// button1
//

this.button1.Location = new System.Drawing.Point(8, 16);
this.button1.Name = button1;
this.button1.Size = new System.Drawing.Size(80, 24);
this.butto, n1.TabIndex = 0;
this.button1.Text = button1;

//
// textBox1
//
this.textBox1.Location = new System.Drawing.Point(112, 16);
this.textBox1.Name = textBox1;
this.textBox1.Size = new System.Drawing.Size(160, 20);
this.textBox1.TabIndex = 1;
this.textBox1.Text = textBox1;
//
// Form1
//

this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
this.ClientSize = new System.Drawing.Size(292, 273);
this.Controls.AddRange(new System.Windows.Forms.Control[] {
this.textBox1,
this.button1});
this.Name = Form1;
this.Text = Form1;
this.ResumeLayout(false);

}
#endregion

[STAThread]

static void Main()
{
Application.Run(new SimpleForm());
}
}
十六、运行时显示自己定义的图标：
//load icon and set to form
System.Drawing.Icon ico = new System.Drawing.Icon(@c: empapp.ico);
this.Icon = ico;
十七、添加组件到ListBox中：
private void Form1_Load(object sender, System.EventArgs e)
{
string str = First item;
int i = 23;
float flt = 34.98f;
listBox1.Items.Add(str);
listBox1.Items.Add(i.ToString());
listBox1.Items.Add(flt.ToString());
listBox1.Items.Add(Last Item in the List Box);
}

网络方面的：
十八、取得IP地址：
using System;
using System.Net;

class GetIP
{
public static void Main()
{
IPHostEntry ipEntry = Dns.GetHostByName (localhost);
IPAddress [] IpAddr = ipEntry.AddressList;
for (int i = 0; i < IpAddr.Length; i++)
{
Console.WriteLine (IP Address {0}: {1} , i, IpAddr.ToString ());
}
}
}
十九、取得机器名称：
using System;
using System.Net;

class GetIP
{
public static void Main()
{
Console.WriteLine (Host name : {0}, Dns.GetHostName());
}
}

二十、发送邮件：
using System;
using System.Web;
using System.Web.Mail;

public class TestSendMail
{
public static void Main()
{
try
{
// Construct a new mail message
MailMessage message = new MailMessage();
message.From = from@domain.com;
message.To = pengyun@cobainsoft.com;
message.Cc = ;
message.Bcc = ;
message.Subject = Subject;
message.Body = Content of message;

//if you want attach file with this mail, add the line below
message.Attachments.Add(new MailAttachment(c:\attach.txt, MailEncoding.Base64));

// Send the message
SmtpMail.Send(message);
System.Console.WriteLine(Message has been sent);
}

catch(Exception ex)
{
System.Console.WriteLine(ex.Message.ToString());
}

}
}
二十一、根据IP地址得出机器名称：
using System;
using System.Net;

class ResolveIP
{
public static void Main()
{
IPHostEntry ipEntry = Dns.Resolve(172.29.9.9);
Console.WriteLine (Host name : {0}, ipEntry.HostName);
}
}

GDI+方面的：
二十二、GDI+入门介绍：
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

public class Form1 : System.Windows.Forms.Form
{
private System.ComponentModel.Container components = null;

public Form1()
{
InitializeComponent();
}

protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}

#region Windows Form Designer generated code
private void InitializeComponent()
{
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
this.ClientSize = new System.Drawing.Size(292, 273);
this.Name = Form1;
this.Text = Form1;
this.Paint += new System.Windows.Forms.PaintEventHandler(this.Form1_Paint);
}
#endregion

[STAThread]
static void Main()
{
Application.Run(new Form1());
}

private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{
Graphics g=e.Graphics;
g.DrawLine(new Pen(Color.Blue),10,10,210,110);
g.DrawRectangle(new Pen(Color.Red),10,10,200,100);
g.DrawEllipse(new Pen(Color.Yellow),10,150,200,100);
}
}

XML方面的：

二十三、读取XML文件：
using System;
using System.Xml;

class TestReadXML
{
public static void Main()
{

XmlTextReader reader = new XmlTextReader(C:\test.xml);
reader.Read();

while (reader.Read())
{
reader.MoveToElement();
Console.WriteLine(XmlTextReader Properties Test);
Console.WriteLine(===================);

// Read this properties of element and display them on console
Console.WriteLine(Name: + reader.Name);
Console.WriteLine(Base URI: + reader.BaseURI);
Console.WriteLine(Local Name: + reader.LocalName);
Console.WriteLine(Attribute Count: + reader.AttributeCount.ToString());
Console.WriteLine(Depth: + reader.Depth.ToString());
Console.WriteLine(Line Number: + reader.LineNumber.ToString());
Console.WriteLine(Node Type: + reader.NodeType.ToString());
Console.WriteLine(Attribute Count: + reader.Value.ToString());
}
}
}
二十四、写XML文件：
using System;
using System.Xml;

public class TestWriteXMLFile
{
public static int Main(string[] args)
{
try
{
// Creates an XML file is not exist
XmlTextWriter writer = new XmlTextWriter(C:\temp\xmltest.xml, null);

// Starts a new document
writer.WriteStartDocument();
//Write comments
writer.WriteComment(Commentss: XmlWriter Test Program);
writer.WriteProcessingInstruction(Instruction,Person Record);
// Add elements to the file
writer.WriteStartElement(p, person, urn:person);
writer.WriteStartElement(LastName,);
writer.WriteString(Chand);
writer.WriteEndElement();
writer.WriteStartElement(FirstName,);
writer.WriteString(Mahesh);
writer.WriteEndElement();
writer.WriteElementInt16(age,, 25);
// Ends the document
writer.WriteEndDocument();
}
catch (Exception e)
{
Console.WriteLine (Exception: {0}, e.ToString());
}
return 0;
}
}

Web Service方面的：
二十五、一个Web Service的小例子：

using System.Web.Services;

public class TestWS : System.Web.Services.WebService
{
[WebMethod()]
public string StringFromWebService()
{
return This is a string from web service.;
}
}

当一个页面跳到此页面时，它就会记录跳到这个页面的ＵＲＬ，然后利用这个ＵＲＬ返回．小技巧，记录下来

1protected void Page_Load(object sender, EventArgs e)
{
ViewState[“UrlReferrer”] = Request.UrlReferrer.ToString();

HyperLink1.NavigateUrl = (string)ViewState[“UrlReferrer”];
Response.Write((string)ViewState[“UrlReferrer”]);