C# 常用代码片段

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:\temp\test.txt
        FileStream fs = new FileStream(@c:\temp\test.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:\temp\test.txt
        FileStream fs = new FileStream(@c:\temp\test.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(\r{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:\test.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:\n{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:\test.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:\test.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：
<%@ Page Language=C# %>
<script runat=server>

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

</script>
<html>
<head>
</head>
<body>
    <form runat=server>
        <p>
            <br />
            Enter your name: <asp:TextBox id=TextBox1 runat=server></asp:TextBox>
        </p>
        <p>
            <b><asp:Label id=Label1 runat=server Width=247px></asp:Label></b>
        </p>
        <p>
            <asp:Button id=Button1 onclick=Button1_Click runat=server Text=Submit></asp:Button>
        </p>
    </form>
</body>
</html>

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.button1.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:\temp\app.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());
    }
}