[转]Regex分组和捕获

The regular expression classes of the .NET framework also support named capture. Unfortunately, the Microsoft developers decided to invent their own syntax, rather than follow the one pioneered by Python. Currently, no other regex flavor supports Microsoft's version of named capture.

Here is an example with two capturing groups in .NET style: (?<first>group)(?'second'group). As you can see, .NET offers two syntaxes to create a capturing group: one using sharp brackets, and the other using single quotes. The first syntax is preferable in strings, where single quotes may need to be escaped. The second syntax is preferable in ASP code, where the sharp brackets are used for HTML tags. You can use the pointy bracket flavor and the quoted flavors interchangeably.

To reference a capturing group inside the regex, use \k<name> or \k'name'. Again, you can use the two syntactic variations interchangeably.

When doing a search-and-replace, you can reference the named group with the familiar dollar sign syntax: ${name}. Simply use a name instead of a number between the curly braces.