asp.net中正则表达式使用(二）

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Regex

Regex 类表示不可变（只读）正则表达式类。它还包含各种静态方法，允许在不显式创建其他类的实例的情况下使用其他正则表达式类。

以下代码示例创建了 Regex 类的实例并在初始化对象时定义一个简单的正则表达式。请注意，使用了附加的反斜杠作为转义字符，它将 \s 匹配字符类中的反斜杠指定为原义字符。

[Visual Basic]    ' Declare object variable of type Regex.    Dim r As Regex     ' Create a Regex object and define its regular expression.    r = New Regex("\s2000")

[C#]    // Declare object variable of type Regex.    Regex r;     // Create a Regex object and define its regular expression.    r = new Regex("\\s2000");

Match

Match 类表示正则表达式匹配操作的结果。以下示例使用 Regex 类的 Match 方法返回 Match 类型的对象，以便找到输入字符串中的第一个匹配项。此示例使用 Match 类的 Match.Success 属性来指示是否已找到匹配。

[Visual Basic]    ' cCreate a new Regex object.    Dim r As New Regex("abc")     ' Find a single match in the input string.    Dim m As Match = r.Match("123abc456")     If m.Success Then        ' Print out the character position where a match was found.         ' (Character position 3 in this case.)        Console.WriteLine("Found match at position " & m.Index.ToString())    End If

[C#]    // Create a new Regex object.    Regex r = new Regex("abc");     // Find a single match in the string.    Match m = r.Match("123abc456");     if (m.Success)     {        // Print out the character position where a match was found.         // (Character position 3 in this case.)        Console.WriteLine("Found match at position " + m.Index);    }

MatchCollection

MatchCollection 类表示成功的非重叠匹配的序列。该集合为不可变（只读）的，并且没有公共构造函数。MatchCollection 的实例是由 Regex.Matches 属性返回的。

以下示例使用 Regex 类的 Matches 方法，通过在输入字符串中找到的所有匹配填充 MatchCollection。该示例将此集合复制到一个字符串数组和一个整数数组中，其中字符串数组用以保存每个匹配项，整数数组用以指示每个匹配项的位置。

[Visual Basic]    Dim mc As MatchCollection    Dim results(20) As String    Dim matchposition(20) As Integer    ' Create a new Regex object and define the regular expression.    Dim r As New Regex("abc")    ' Use the Matches method to find all matches in the input string.    mc = r.Matches("123abc4abcd")    ' Loop through the match collection to retrieve all     ' matches and positions.    Dim i As Integer    For i = 0 To mc.Count - 1        ' Add the match string to the string array.        results(i) = mc(i).Value        ' Record the character position where the match was found.        matchposition(i) = mc(i).Index    Next i

[C#]    MatchCollection mc;    String[] results = new String[20];    int[] matchposition = new int[20];        // Create a new Regex object and define the regular expression.    Regex r = new Regex("abc");     // Use the Matches method to find all matches in the input string.    mc = r.Matches("123abc4abcd");    // Loop through the match collection to retrieve all     // matches and positions.    for (int i = 0; i < mc.Count; i++)     {        // Add the match string to the string array.           results[i] = mc[i].Value;        // Record the character position where the match was found.        matchposition[i] = mc[i].Index;       }

GroupCollection

GroupCollection 类表示捕获的组的集合并返回单个匹配中捕获的组的集合。该集合为不可变（只读）的，并且没有公共构造函数。GroupCollection 的实例在 Match.Groups 属性返回的集合中返回。

以下控制台应用程序示例查找并输出由正则表达式捕获的组的数目。有关如何提取组集合的每一成员中的各个捕获项的示例，请参见下面一节的 Capture Collection 示例。

[Visual Basic]    Imports System    Imports System.Text.RegularExpressions    Public Class RegexTest        Public Shared Sub RunTest()            ' Define groups "abc", "ab", and "b".            Dim r As New Regex("(a(b))c")             Dim m As Match = r.Match("abdabc")            Console.WriteLine("Number of groups found = " _            & m.Groups.Count.ToString())        End Sub                Public Shared Sub Main()            RunTest()        End Sub    End Class

[C#]    using System;    using System.Text.RegularExpressions;    public class RegexTest     {        public static void RunTest()         {            // Define groups "abc", "ab", and "b".            Regex r = new Regex("(a(b))c");             Match m = r.Match("abdabc");            Console.WriteLine("Number of groups found = " + m.Groups.Count);        }        public static void Main()         {            RunTest();        }    }

该示例产生下面的输出。

[Visual Basic]    Number of groups found = 3

[C#]    Number of groups found = 3

CaptureCollection

CaptureCollection 类表示捕获的子字符串的序列，并且返回由单个捕获组执行的捕获的集合。由于限定符，捕获组可以在单个匹配中捕获多个字符串。Captures 属性（CaptureCollection 类的对象）是作为 Match 和 group 类的成员提供的，以便于对捕获的子字符串的集合的访问。

例如，如果使用正则表达式 ((a(b))c)+（其中 + 限定符指定一个或多个匹配）从字符串“abcabcabc”中捕获匹配，则子字符串的每一匹配的 Group 的 CaptureCollection 将包含三个成员。

以下控制台应用程序示例使用正则表达式 (Abc)+ 来查找字符串“XYZAbcAbcAbcXYZAbcAb”中的一个或多个匹配。该示例阐释了使用 Captures 属性来返回多组捕获的子字符串。

[Visual Basic]    Imports System    Imports System.Text.RegularExpressions    Public Class RegexTest        Public Shared Sub RunTest()            Dim counter As Integer            Dim m As Match            Dim cc As CaptureCollection            Dim gc As GroupCollection            ' Look for groupings of "Abc".            Dim r As New Regex("(Abc)+")             ' Define the string to search.            m = r.Match("XYZAbcAbcAbcXYZAbcAb")            gc = m.Groups                        ' Print the number of groups.            Console.WriteLine("Captured groups = " & gc.Count.ToString())                        ' Loop through each group.            Dim i, ii As Integer            For i = 0 To gc.Count - 1                cc = gc(i).Captures                counter = cc.Count                                ' Print number of captures in this group.                Console.WriteLine("Captures count = " & counter.ToString())                                ' Loop through each capture in group.                            For ii = 0 To counter - 1                    ' Print capture and position.                    Console.WriteLine(cc(ii).ToString() _                        & "   Starts at character " & cc(ii).Index.ToString())                Next ii            Next i        End Sub            Public Shared Sub Main()            RunTest()         End Sub    End Class

[C#]    using System;    using System.Text.RegularExpressions;    public class RegexTest         {        public static void RunTest()         {            int counter;            Match m;            CaptureCollection cc;            GroupCollection gc;            // Look for groupings of "Abc".            Regex r = new Regex("(Abc)+");             // Define the string to search.            m = r.Match("XYZAbcAbcAbcXYZAbcAb");             gc = m.Groups;            // Print the number of groups.            Console.WriteLine("Captured groups = " + gc.Count.ToString());            // Loop through each group.            for (int i=0; i < gc.Count; i++)             {                cc = gc[i].Captures;                counter = cc.Count;                                // Print number of captures in this group.                Console.WriteLine("Captures count = " + counter.ToString());                                // Loop through each capture in group.                for (int ii = 0; ii < counter; ii++)                 {                    // Print capture and position.                    Console.WriteLine(cc[ii] + "   Starts at character " +                         cc[ii].Index);                }            }        }        public static void Main() {            RunTest();        }    }

此示例返回下面的输出结果。

[Visual Basic]    Captured groups = 2    Captures count = 1    AbcAbcAbc   Starts at character 3    Captures count = 3    Abc   Starts at character 3    Abc   Starts at character 6    Abc   Starts at character 9

[C#]    Captured groups = 2    Captures count = 1    AbcAbcAbc   Starts at character 3    Captures count = 3    Abc   Starts at character 3    Abc   Starts at character 6    Abc   Starts at character 9

Group

group 类表示来自单个捕获组的结果。因为 Group 可以在单个匹配中捕获零个、一个或更多的字符串（使用限定符），所以它包含 Capture 对象的集合。因为 Group 继承自 Capture，所以可以直接访问最后捕获的子字符串（Group 实例本身等价于 Captures 属性返回的集合的最后一项）。

Group 的实例是由 Match.Groups(groupnum) 属性返回的，或者在使用“(?<groupname>)”分组构造的情况下，是由 Match.Groups("groupname") 属性返回的。

以下代码示例使用嵌套的分组构造来将子字符串捕获到组中。

[Visual Basic]    Dim matchposition(20) As Integer    Dim results(20) As String    ' Define substrings abc, ab, b.    Dim r As New Regex("(a(b))c")     Dim m As Match = r.Match("abdabc")    Dim i As Integer = 0    While Not (m.Groups(i).Value = "")           ' Copy groups to string array.       results(i) = m.Groups(i).Value            ' Record character position.        matchposition(i) = m.Groups(i).Index         i = i + 1    End While

[C#]    int[] matchposition = new int[20];    String[] results = new String[20];    // Define substrings abc, ab, b.    Regex r = new Regex("(a(b))c");     Match m = r.Match("abdabc");    for (int i = 0; m.Groups[i].Value != ""; i++)     {        // Copy groups to string array.        results[i]=m.Groups[i].Value;         // Record character position.        matchposition[i] = m.Groups[i].Index;     }

此示例返回下面的输出结果。

[Visual Basic]    results(0) = "abc"   matchposition(0) = 3    results(1) = "ab"    matchposition(1) = 3    results(2) = "b"     matchposition(2) = 4

[C#]    results[0] = "abc"   matchposition[0] = 3    results[1] = "ab"    matchposition[1] = 3    results[2] = "b"     matchposition[2] = 4

以下代码示例使用命名的分组构造，从包含“DATANAME:VALUE”格式的数据的字符串中捕获子字符串，正则表达式通过冒号“:”拆分数据。

[Visual Basic]    Dim r As New Regex("^(?<name>\w+):(?<value>\w+)")    Dim m As Match = r.Match("Section1:119900")

[C#]    Regex r = new Regex("^(?<name>\\w+):(?<value>\\w+)");    Match m = r.Match("Section1:119900");

此正则表达式返回下面的输出结果。

[Visual Basic]    m.Groups("name").Value = "Section1"    m.Groups("value").Value = "119900"

[C#]    m.Groups["name"].Value = "Section1"    m.Groups["value"].Value = "119900"

Capture

Capture 类包含来自单个子表达式捕获的结果。

以下示例在 Group 集合中循环，从 Group 的每一成员中提取 Capture 集合，并且将变量 posn 和 length 分别分配给找到每一字符串的初始字符串中的字符位置，以及每一字符串的长度。

[Visual Basic]    Dim r As Regex    Dim m As Match    Dim cc As CaptureCollection    Dim posn, length As Integer    r = New Regex("(abc)*")    m = r.Match("bcabcabc")    Dim i, j As Integer    i = 0    While m.Groups(i).Value <> ""        ' Grab the Collection for Group(i).        cc = m.Groups(i).Captures        For j = 0 To cc.Count - 1            ' Position of Capture object.            posn = cc(j).Index            ' Length of Capture object.            length = cc(j).Length        Next j        i += 1    End While

[C#]    Regex r;    Match m;    CaptureCollection cc;    int posn, length;    r = new Regex("(abc)*");    m = r.Match("bcabcabc");    for (int i=0; m.Groups[i].Value != ""; i++)     {        // Capture the Collection for Group(i).        cc = m.Groups[i].Captures;         for (int j = 0; j < cc.Count; j++)         {            // Position of Capture object.            posn = cc[j].Index;             // Length of Capture object.            length = cc[j].Length;         }    }

private void button1_Click(object sender, System.EventArgs e)
   {
    Regex regexTest = new Regex(@"[0-9]H",RegexOptions.IgnoreCase);
    Match match = regexTest.Match(this.textBox1.Text);
    System.Text.StringBuilder strb = new System.Text.StringBuilder();

GroupCollection groups = match.Groups;

    #region "while"
    while (match.Success)
    {
     if (strb.Length == 0)
     {
      strb.Append("Match Succeeded!");
     }
     for (int index = 0;index < groups.Count;index++)
     {
      strb.Append(Environment.NewLine);
      strb.Append(groups[index].Value);
     }
     match = match.NextMatch();
    }
    #endregion

    if (strb.Length == 0)
    {
     strb.Append("Match Failed!");
    }
    this.textBox2.Text = strb.ToString();

}