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();
catch (Exception e)
conn.Close();
}
{
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();
= new DataSet();
DataSet ds
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();
= new DataSet();
DataSet ds
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.";
}
}
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