c# - 匹配重复模式

Question

我目前正在尝试在以下输入中匹配和捕获文本：

field: one two three field: "moo cow" field: +this

我可以匹配field:，[a-z]*\:但是我似乎无法匹配其余的内容，到目前为止，我的尝试只导致捕获所有我不想做的事情。

Answer 1

如果您知道它总是字面意思field:，则绝对不需要正则表达式：

var delimiters = new String[] {"field:"};
string[] values = input.Split(delimiters, StringSplitOptions.RemoveEmptyEntries);

---

但是，根据您的正则表达式，我假设名称field可以有所不同，只要它位于冒号前面。您可以尝试捕捉一个单词:，然后捕捉到下一个单词的所有内容（使用前瞻）。

foreach(Match match in Regex.Matches(input, @"([a-z]+):((?:(?![a-z]+:).)*)"))
{
    string fieldName = match.Groups[1].Value;
    string value = match.Groups[2].Value;
}

正则表达式的解释：

(     # opens a capturing group; the content can later be accessed with Groups[1]
[a-z] # lower-case letter
+     # one or more of them
)     # end of capturing group
:     # a literal colon
(     # opens a capturing group; the content can later be accessed with Groups[2]
(?:   # opens a non-capturing group; just a necessary subpattern which we do not
      # need later any more
(?!   # negative lookahead; this will NOT match if the pattern inside matches
[a-z]+:
      # a word followed by a colon; just the same as we used at the beginning of
      # the regex
)     # end of negative lookahead (not that this does not consume any characters;
      # it LOOKS ahead)
.     # any character (except for line breaks)
)     # end of non-capturing group
*     # 0 or more of those
)     # end of capturing group

所以首先我们匹配anylowercaseword:。然后我们一次再匹配一个字符，每个字符都检查这个字符不是anotherlowercaseword:. 使用捕获组，我们稍后可以分别找到字段的名称和字段的值。

Answer 2

不要忘记您实际上可以匹配正则表达式中的文字字符串。如果你的模式是这样的：

field\:

您将按字面意思匹配“字段：”，仅此而已。