正则表达式 - 带替换的可选组

Question

I need to capture up to four digits, as follows, in a named group:

    123       -> 123
    2357      -> 2357
    123 (11X) -> 11
    235 (7Y)  -> 7

As you can see, the bracketed number and letter is optional. Though there appear to be similar questions on the forum, my limited knowledge prevents me from adapting their solutions.

My initial attempt is, as follows:

(?<ABC>\d{0,4})?|\((?<DEF>\d{0,4})(?<GHI>[A-Za-z])\)

Debuggex Demo seems to capture the groups I need, but how do I automatically choose the correct group in a replacement context - ABC or DEF depending on the input?

Do I need a 'branch reset' so that I can give groups 'ABC' and 'DEF' the same name and, if so, how do I implement it?

Please advise?

Answer 1

经过多次反复试验，以下模式适用于 .NET [解决方案]：

    (?<ABC>\d{0,4}) ?\((?<ABC>\d{0,4})(?<GHI>[A-Za-z])?\)