仅更换某些群体与正则表达式 [英] Replace only some groups with Regex

问题描述

让我们假设我有以下的正则表达式：

Let's suppose I have the following regex:

-(\d+)-

和我想更换，使用C＃，集团1 （\\ d +）与 AA ，获得

and I want to replace, using C#, the Group 1 (\d+) with AA, to obtain:

-AA-

现在我用替换它：

var text = "example-123-example";
var pattern = @"-(\d+)-";
var replaced = Regex.Replace(text, pattern, "-AA-"); 

但我真的不喜欢这一点，因为如果我改变的模式来匹配 _（\\ d +）_ 相反，我将不得不更改替换字符串 _AA _ 过了，这是违反了DRY原则。

But I don't really like this, because if I change the pattern to match _(\d+)_ instead, I will have to change the replacement string by _AA_ too, and this is against the DRY principle.

我在寻找类似：

请匹配的文本它究竟是怎么回事，但更改1组由本文和2组其他文本 ...

Keep the matched text exactly how it is, but change Group 1 by this text and Group 2 by another text...

编辑：结果
这只是一个例子。我只是在寻找做我上面所说的通用方法。

That was just an example. I'm just looking for a generic way of doing what I said above.

这应该工作：

东西（\\ d +）more_text 键，你能想象的任何图案。

anything(\d+)more_text and any pattern you can imagine.

所有我想要做的是仅更换群体，并保持了比赛的其余部分。

All I want to do is replace only groups, and keep the rest of the match.

推荐答案

一个好主意，可能是里面封装一切群体，不管需要识别它们。这样，你可以在替换字符串中使用它们。例如：

A good idea could be to encapsulate everything inside groups, no matter if need to identify them or not. That way you can use them in your replacement string. For example:

var pattern = @"(-)(\d+)(-)";
var replaced = Regex.Replace(text, pattern, "$1AA$3"); 

或使用MatchEvaluator：

or using a MatchEvaluator:

var replaced = Regex.Replace(text, pattern, m => m.Groups[1].Value + "AA" + m.Groups[3].Value);

---

另一种方式，稍显凌乱，可以使用后向/前瞻：

---

Another way, slightly messy, could be using a lookbehind/lookahead:

（小于？= - ）（\\ d +）（？= - ）

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