C# 常用代码片段
2024-10-20 13:44:14
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());
}
}
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