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."; }}
