在正则表达式命名的捕获组 [英] named capture group in regex

问题描述

我需要一个正则表达式来捕获从以下字符串的数字和连字符帮助： 一些文字和东西200-1234EM一些其他的东西

它也可以出现无hypenated部分： 一些文字123EM其他文本

我需要的不是200-1234，或在一个名为捕获组123。

我尝试这样做： \ B（[0-9] {0,3} \ - {0,1} [0-9] {3}）EM \ b

这确实匹配，但是它不是一个命名组。

当我尝试命名该组是这样的： \ B（＆LT;试验＆gt; [0-9] {0,3} \ - {0,1} [0-9] {3}）EM \ b 我得到一个错误信息未知看看隐藏组近34指数

我需要这在.NET正则表达式类的工作。

谢谢！

解决方案

  resultString = Regex.Match（subjectString，@\ B（＆LT;数量＆GT; \ D +（？：？ - ？\ d +））EM \ B）组。[数量]值。
 

这应该做的伎俩。如果你提供更多的投入，我可以使其更加坚固。

说明：

  @
\ B＃在单词边界断言位置
（LT;数＆GT;＃匹配正EX $ P $下面pssion并捕获其匹配到的反向引用名称为数字
   \ D＃匹配单个数字0..9
      +＃之间的一个，不限次数，多次越好，需要回馈（贪婪）
   （？：＃匹配下面的常规EX pression
       - ＃匹配字符 - 从字面上
      \ D＃匹配单个数字0..9
         +＃之间的一个，不限次数，多次越好，需要回馈（贪婪）
   ）？ ＃零至1次，多次越好，需要回馈（贪婪）
）
EM＃匹配字符EM的字面
\ B＃在单词边界断言位置

 

I need help with a regex to capture the numbers and hyphen from the following string: "some text and stuff 200-1234EM some other stuff"

It can also appear without the hypenated part: "some text 123EM other text"

I need either "200-1234" or "123" in a named capture group.

I tried this: \b([0-9]{0,3}\-{0,1}[0-9]{3})EM\b

It does match, but it is not a named group.

When I try to name the group like this: \b(?<test>[0-9]{0,3}\-{0,1}[0-9]{3})EM\b I get an error message "Unknown look-behind group near index 34"

I need this to work in the .NET RegEx class

Thanks!

解决方案

resultString = Regex.Match(subjectString, @"\b(?<number>\d+(?:-\d+)?)EM\b").Groups["number"].Value;

This should do the trick. If you provide more input I could make it more robust.

Explanation:

    @"
\b            # Assert position at a word boundary
(?<number>    # Match the regular expression below and capture its match into backreference with name "number"
   \d            # Match a single digit 0..9
      +             # Between one and unlimited times, as many times as possible, giving back as needed (greedy)
   (?:           # Match the regular expression below
      -             # Match the character "-" literally
      \d            # Match a single digit 0..9
         +             # Between one and unlimited times, as many times as possible, giving back as needed (greedy)
   )?            # Between zero and one times, as many times as possible, giving back as needed (greedy)
)
EM            # Match the characters "EM" literally
\b            # Assert position at a word boundary
"

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