如何在C＃中读取RegEx捕获

我开始写一本C＃书，我决定把RegEx放到混音中，让枯燥的控制台练习更有趣。 我想要做的是在控制台中询问用户他们的电话号码，根据RegEx进行检查，然后捕获数字，以便我可以按照我想要的方式对其进行格式化。 除了RegEx捕获部分之外，我已经完成了所有工作。 如何将捕获值转换为C＃变量？

也可以随意更正任何代码格式或变量命名问题。

static void askPhoneNumber() { String pattern = @"[(]?(\d{3})[)]?[ -.]?(\d{3})[ -.]?(\d{4})"; System.Console.WriteLine("What is your phone number?"); String phoneNumber = Console.ReadLine(); while (!Regex.IsMatch(phoneNumber, pattern)) { Console.WriteLine("Bad Input"); phoneNumber = Console.ReadLine(); } Match match = Regex.Match(phoneNumber, pattern); Capture capture = match.Groups.Captures; System.Console.WriteLine(capture[1].Value + "-" + capture[2].Value + "-" + capture[3].Value); } 

Answer 1

C＃正则表达式API可能非常令人困惑。 有团体和捕获 ：

• 组表示捕获组，它用于从文本中提取子字符串
• 如果组出现在量词中，则每组可以有多个捕获 。

层次结构是：

• 比赛
  • 组
    • 捕获

（一个匹配可以有几个组，每个组可以有几个捕获）

例如：

 Subject: aabcabbc Pattern: ^(?:(a+b+)c)+$ 

在此示例中，只有一个组： (a+b+) 。 该组位于量词内，并且匹配两次。 它会生成两个捕获 ： aab和abb ：

 aabcabbc ^^^ ^^^ Cap1 Cap2 

当一个组不在量词内时，它只生成一个捕获。 在您的情况下，您有3个组，每组捕获一次。 您可以使用match.Groups[1].Value ， match.Groups[2].Value和match.Groups[3].Value来提取您感兴趣的3个子串，而不需要match.Groups[3].Value 捕获概念。

Answer 2

 string pattern = @"[(]?(\d{3})[)]?[ -.]?(\d{3})[ -.]?(\d{4})"; System.Console.WriteLine("What is your phone number?"); string phoneNumber = Console.ReadLine(); while (!Regex.IsMatch(phoneNumber, pattern)) { Console.WriteLine("Bad Input"); phoneNumber = Console.ReadLine(); } var match = Regex.Match(phoneNumber, pattern); if (match.Groups.Count == 4) { System.Console.WriteLine("Number matched : "+match.Groups[0].Value); System.Console.WriteLine(match.Groups[1].Value + "-" + match.Groups[2].Value + "-" + match.Groups[3].Value); } 

Answer 3

匹配结果可能很难理解。 我写了这段代码，以帮助我理解已找到的内容和位置。 目的是将输出的部分（来自标有//**的行）复制到程序中以利用匹配中找到的值。

 public static void DisplayMatchResults(Match match) { Console.WriteLine("Match has {0} captures", match.Captures.Count); int groupNo = 0; foreach (Group mm in match.Groups) { Console.WriteLine(" Group {0,2} has {1,2} captures '{2}'", groupNo, mm.Captures.Count, mm.Value); int captureNo = 0; foreach (Capture cc in mm.Captures) { Console.WriteLine(" Capture {0,2} '{1}'", captureNo, cc); captureNo++; } groupNo++; } groupNo = 0; foreach (Group mm in match.Groups) { Console.WriteLine(" match.Groups[{0}].Value == \"{1}\"", groupNo, match.Groups[groupNo].Value); //** groupNo++; } groupNo = 0; foreach (Group mm in match.Groups) { int captureNo = 0; foreach (Capture cc in mm.Captures) { Console.WriteLine(" match.Groups[{0}].Captures[{1}].Value == \"{2}\"", groupNo, captureNo, match.Groups[groupNo].Captures[captureNo].Value); //** captureNo++; } groupNo++; } } 

给出此输入的一个使用此方法的简单示例：

 Regex regex = new Regex("/([A-Za-z]+)/(\\d+)$"); String text = "some/directory/Pictures/Houses/12/apple/banana/" + "cherry/345/damson/elderberry/fig/678/gooseberry"); Match match = regex.Match(text); DisplayMatchResults(match); 

输出是：

 Match has 1 captures Group 0 has 1 captures '/Houses/12' Capture 0 '/Houses/12' Group 1 has 1 captures 'Houses' Capture 0 'Houses' Group 2 has 1 captures '12' Capture 0 '12' match.Groups[0].Value == "/Houses/12" match.Groups[1].Value == "Houses" match.Groups[2].Value == "12" match.Groups[0].Captures[0].Value == "/Houses/12" match.Groups[1].Captures[0].Value == "Houses" match.Groups[2].Captures[0].Value == "12" 

假设我们想要在上面的文本中找到上述正则表达式的所有匹配项。 然后我们可以在代码中使用MatchCollection ，例如：

 MatchCollection matches = regex.Matches(text); for (int ii = 0; ii < matches.Count; ii++) { Console.WriteLine("Match[{0}] // of 0..{1}:", ii, matches.Count-1); RegexMatchDisplay.DisplayMatchResults(matches[ii]); } 

这个输出是：

 Match[0] // of 0..2: Match has 1 captures Group 0 has 1 captures '/Houses/12/' Capture 0 '/Houses/12/' Group 1 has 1 captures 'Houses' Capture 0 'Houses' Group 2 has 1 captures '12' Capture 0 '12' match.Groups[0].Value == "/Houses/12/" match.Groups[1].Value == "Houses" match.Groups[2].Value == "12" match.Groups[0].Captures[0].Value == "/Houses/12/" match.Groups[1].Captures[0].Value == "Houses" match.Groups[2].Captures[0].Value == "12" Match[1] // of 0..2: Match has 1 captures Group 0 has 1 captures '/cherry/345/' Capture 0 '/cherry/345/' Group 1 has 1 captures 'cherry' Capture 0 'cherry' Group 2 has 1 captures '345' Capture 0 '345' match.Groups[0].Value == "/cherry/345/" match.Groups[1].Value == "cherry" match.Groups[2].Value == "345" match.Groups[0].Captures[0].Value == "/cherry/345/" match.Groups[1].Captures[0].Value == "cherry" match.Groups[2].Captures[0].Value == "345" Match[2] // of 0..2: Match has 1 captures Group 0 has 1 captures '/fig/678/' Capture 0 '/fig/678/' Group 1 has 1 captures 'fig' Capture 0 'fig' Group 2 has 1 captures '678' Capture 0 '678' match.Groups[0].Value == "/fig/678/" match.Groups[1].Value == "fig" match.Groups[2].Value == "678" match.Groups[0].Captures[0].Value == "/fig/678/" match.Groups[1].Captures[0].Value == "fig" match.Groups[2].Captures[0].Value == "678" 

因此：

  matches[1].Groups[0].Value == "/cherry/345/" matches[1].Groups[1].Value == "cherry" matches[1].Groups[2].Value == "345" matches[1].Groups[0].Captures[0].Value == "/cherry/345/" matches[1].Groups[1].Captures[0].Value == "cherry" matches[1].Groups[2].Captures[0].Value == "345" 

类似地， matches[0]和matches[2] 。