如何在Regex.Replace中将匹配项替换为替换字符串？

Question

I need the match in the Regex.Replace to be part of the replacement string. For example, if I want to change DOMAIN to <a>DOMAIN</a> , wherever it says DOMAIN. How do I get DOMAIN into the match?

regex.Replace(input, String.Format("<a>{0}</a>" WHAT_HERE?));

How do I find the "WHAT_HERE?"?

Answer 1

You can use a grouping construct (...) :

string replaced = Regex.Replace("<input>", "(DOMAIN)", "<a>$1</a>");

Example: https://dotnetfiddle.net/Hu0cEO

Answer 2

Andrew's answer is correct, here's how you'd do it if you wanted to name the grouping and then replace it by name (expanded from Andrew's dotnetfiddle):

using System;
using System.Text.RegularExpressions;

public class Program
{
    public static void Main()
    {
        string result = Regex.Replace("This is a test to see if DOMAIN gets replaced properly. DOMAIN", "(?<myName>DOMAIN)", "<a>${myName}</a>");

        result.Dump();
    }
}

Output:

This is a test to see if <a>DOMAIN</a> gets replaced properly. <a>DOMAIN</a>