2008年5月19日随笔档案 - 大宋提刑官

静态构造函数用于初始化任何静态数据，或用于执行仅需执行一次的特定操作。在创建第一个实例或引用任何静态成员之前，将自动调用静态构造函数。

1

class SimpleClass
2

{
3

// Static constructor
4

static SimpleClass()
5

{
6

//

7

}
8

}

静态构造函数具有以下特点：

静态构造函数既没有访问修饰符，也没有参数。
在创建第一个实例或引用任何静态成员之前，将自动调用静态构造函数来初始化类。
无法直接调用静态构造函数。
在程序中，用户无法控制何时执行静态构造函数。
静态构造函数的典型用途是：当类使用日志文件时，将使用这种构造函数向日志文件中写入项。
静态构造函数在为非托管代码创建包装类时也很有用，此时该构造函数可以调用 LoadLibrary 方法。

示例
在此示例中，类 Bus 有一个静态构造函数和一个静态成员 Drive()。当调用 Drive() 时，将调用静态构造函数来初始化类。

1

public class Bus
2

{
3

// Static constructor:
4

static Bus()
5

{
6

System.Console.WriteLine("The static constructor invoked.");
7

}
8

9

public static void Drive()
10

{
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System.Console.WriteLine("The Drive method invoked.");
12

}
13

}
14

15

class TestBus
16

{
17

static void Main()
18

{
19

Bus.Drive();
20

}
21

}

输出

The static constructor invoked.

The Drive method invoked.

链接：http://www.csharphelp.com/archives4/archive693.html

1

GetUrls urls = new GetUrls(); urls.RetrieveUrls("http://www.microsoft.com");
2

3

4

The class is listed below. Have fun!
5

//required namespaces
6

using System;
7

using System.Collections.Generic;
8

using System.Text;
9

using System.Net;
10

using System.IO;
11

using System.Text.RegularExpressions;
12

13

14

namespace FindAllUrls
15

{
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class GetUrls
17

{
18

19

//public method called from your application
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public void RetrieveUrls( string webPage )
21

{
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GetAllUrls(RetrieveContent(webPage));
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}
24

25

//get the content of the web page passed in
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private string RetrieveContent(string webPage)
27

{
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HttpWebResponse response = null;//used to get response
29

StreamReader respStream = null;//used to read response into string
30

try
31

{
32

//create a request object using the url passed in
33

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(webPage);
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request.Timeout = 10000;
35

36

//go get a response from the page
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response = (HttpWebResponse)request.GetResponse();
38

39

//create a streamreader object from the response
40

respStream = new StreamReader(response.GetResponseStream());
41

42

//get the contents of the page as a string and return it
43

return respStream.ReadToEnd();
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}
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catch (Exception ex)//houston we have a problem!
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{
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throw ex;
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}
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finally
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{
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//close it down, we're going home!
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response.Close();
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respStream.Close();
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}
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}
56

57

//using a regular expression, find all of the href or urls
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//in the content of the page
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private void GetAllUrls( string content )
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{
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//regular expression
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.*?)(?:[\s>""'])";
64

65

//Set up regex object
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Regex RegExpr = new Regex(pattern, RegexOptions.IgnoreCase);
67

68

//get the first match
69

Match match = RegExpr.Match(content);
70

71

//loop through matches
72

while (match.Success)
73

{
74

75

//output the match info
76

Console.WriteLine("href match: " + match.Groups[0].Value);
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WriteToLog("C:\matchlog.txt", "href match: " + match.Groups[0].Value + "\r\n");
78

79

Console.WriteLine("Url match: " + match.Groups[1].Value);
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WriteToLog("C:\matchlog.txt", "Url | Location | mailto match: " + match.Groups[1].Value + "\r\n");
81

82

//get next match
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match = match.NextMatch();
84

}
85

}
86

87

//Write to a log file
88

private void WriteToLog(string file, string message)
89

{
90

using (StreamWriter w = File.AppendText(file))
91

{
92

w.WriteLine(DateTime.Now.ToString() + ": " + message); w.Close();
93

}
94

}
95

}
96

}
97

98

链接：http://www.csharphelp.com/archives4/archive694.html

From Decimal to Binary...

 1using System;

 2

 3class Program{

 4

 5   static void Main(string[] args){

 6

 7      try{

 8        

 9  int i = (int)Convert.ToInt64(args[0]);

10         Console.WriteLine("\n{0} converted to Binary is {1}\n",i,ToBinary(i));

11      

12      }catch(Exception e){

13        

14         Console.WriteLine("\n{0}\n",e.Message);

15 

16      }

17

18   }//end Main

19

20

21  public static string ToBinary(Int64 Decimal)

22  {

23   // Declare a few variables we're going to need

24   Int64 BinaryHolder;

25   char[] BinaryArray;

26   string BinaryResult = "";

27

28   while (Decimal > 0)

29   {

30    BinaryHolder = Decimal % 2;

31    BinaryResult += BinaryHolder;

32    Decimal = Decimal / 2;

33   }

34

35   // The algoritm gives us the binary number in reverse order (mirrored)

36   // We store it in an array so that we can reverse it back to normal

37   BinaryArray = BinaryResult.ToCharArray();

38   Array.Reverse(BinaryArray);

39   BinaryResult = new string(BinaryArray);

40

41   return BinaryResult;

42  }

43

44

45}//end class Program

46

--------------------------------------------------------------------------------

From Binary to Decimal...

 1using System;

 2

 3class Program{

 4

 5   static void Main(string[] args){

 6

 7      try{

 8        

 9         int i = ToDecimal(args[0]);

10         Console.WriteLine("\n{0} converted to Decimal is {1}",args[0],i);

11      

12      }catch(Exception e){

13        

14         Console.WriteLine("\n{0}\n",e.Message);

15 

16      }

17

18   }//end Main

19

20

21                public static int ToDecimal(string bin)

22  {

23                    long l = Convert.ToInt64(bin,2);

24                    int i = (int)l;

25                    return i;

26  }

27

28

29}//end class Program

30

31

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