C#入门代码集

在QQ群聊天中，曾经有人问一些基础性问题。现在这里提供C#基本入门的代码集合20个，涵盖下面
基础语法;ADO.NET方面的;网络方面的：XML方面的：Web Service方面的.

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();
    }
}

 

网络方面的：
十四、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());
        }
    }
}

十五：取得机器名称：

using System;
using System.Net;

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

十六：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());
        }

    }
}

十七：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);
    }
}

XML方面的：
十八：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());
        }
    }
}

十九：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", "urnerson");
            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、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.";
    }
}