C# Regex - 如何从字符串中删除多个成对的括号

Question

我正在尝试弄清楚如何使用 C# 正则表达式从字符串中删除所有成对括号的实例。应删除括号和它们之间的所有文本。括号并不总是在同一行。此外，它们可能是嵌套的括号。字符串的一个例子是

This is a (string). I would like all of the (parentheses
to be removed). This (is) a string. Nested ((parentheses) should) also
be removed. (Thanks) for your help.

所需的输出应如下所示:

This is a . I would like all of the . This  a string. Nested  also
be removed.  for your help.

Answer 1

幸运的是，.NET 允许在正则表达式中递归(参见 Balancing Group Definitions):

Regex regexObj = new Regex(
    @"\(              # Match an opening parenthesis.
      (?>             # Then either match (possessively):
       [^()]+         #  any characters except parentheses
      |               # or
       \( (?<Depth>)  #  an opening paren (and increase the parens counter)
      |               # or
       \) (?<-Depth>) #  a closing paren (and decrease the parens counter).
      )*              # Repeat as needed.
     (?(Depth)(?!))   # Assert that the parens counter is at zero.
     \)               # Then match a closing parenthesis.",
    RegexOptions.IgnorePatternWhitespace);

如果有人想知道:“括号计数器”可能永远不会低于零(<?-Depth> 否则会失败)，所以即使括号是“平衡的”但没有正确匹配(如 ()))((() )，这个正则表达式不会被愚弄。

有关更多信息，请阅读 Jeffrey Friedl 的优秀著作 "Mastering Regular Expressions" (第 436 页)