1. 获取“我的文档”等一些系统文件夹路径
    MessageBox.Show(Environment.GetFolderPath(Environment.SpecialFolder.Personal));
2. 确定当前运行的系统
    OperatingSystem os  = Environment.OSVersion;
    MessageBox.Show(os.Version.ToString());
    MessageBox.Show(os.Platform.ToString());
3. 模拟触发buttonclick事件
    button1.PerformClick();
4. 创建一个可改变大小没有标题栏的窗体
    form1.Test = string.Empty;
    form1.ControlBox = false;
5. 如何在.NET的Windows窗体上启用XP主题集？（How to use XP Themes with Windows Forms using the .NET?）
    确认你的控件中FlatStyle属性已经修改为System，再修改Main方法。
    static void Main()
{
    Application.EnableVisualStyles();
    Application.DoEvents();
    Application.Run(new Form1());
}
6. 为一个窗体设置一个默认按钮
     form1.AcceptButton = button1;
7. 为一个窗体设置一个取消按钮
     form1.CancelButton = button1;
8. 用现有可用字体绑定到ComboBox控件
    comboBox1.Items.AddRange(FontFamily.Families);
9. 清理语句
    private bool Disposed;
    private void Disposed()
{
    if(Disposed)
      return;
    
    Disposed = true;
    GC.SuppressFinalize(this);
}
10. 声明索引属性
      public String this[String name]
{
      get
    {
        retrun (String) lookuptable[name];
    }
}
11. 访问索引属性
       String s = Request.QueryString["Name"];
       String value = Request.Cookies["Key"];
12. 声明简单属性
       public string name
{
      get
    {
        ....
                    return......;
    }
      set
    {
        .......=value;
    }
}
13.  声明和使用枚举
// Declare the Enumeration
       public enum MessageSize
    {
      Small = 0,
      Medium =1,
      Large = 2
    }
// Creat a Field or Property
      public MessageSize msgsize;

// Assign to the property using the Enumeration values
      msgsize = Small;
14. 枚举集合
      foreach (String s in coll) {
}
15. 声明和使用方法
      // Declare a void return function
      void voidfunction() {
       .......
}

// Declare a function tha retruns a value
       String stirngfunction() {
          .............
             return (String) val;
}

// Declare a function that takes and returns values
      String parmfunction(String a , String b) {
               .........
              return (String) (a + b);
}

// Use the Functions
voidfunction();
String s1 = stringfunction();
String s2 = parmfunction("Hello","World!");
16. 自定义特性
// Stand-alone attribute
[STAThread]

// Attribute with parameters
[DllImport("ADVAPI32.DLL"]

// Attribute with named parameters
[DllImport("KERNEL32.DLL",CharSet = CharSet.Auto)]
17. 数组
     String[] a = new String[3];
     a[0] ="1";
     a[1] ="2";
     a[2] = "3";

    String[][] a = new String[3][3];
     a[0][0] = "1";
     a[1][0] = "2";
     a[2][0] = "3";
18. 初始化
     String s= "Hello , World!";
     int i = 2;
     double[] a = {3.00,4.00,5.00};
19. If 语句
     if(Request .QueryString != null) {
         ......
}
20. Case语句
     switch (FirstName) {
       case "John" :
               ......
              break;
       case"Paul" :
              ..........
             break;
       case"Ringo" :
             .........
             break;
       dafault :
             ...........
             break;
}