regex.replace不适用于带有“ $”的模式-C＃

Question

I've tried to replace user name in Git's URL, by using Regex.replace() .

The reason I want to use Regex.Replace instead of string.Replace is because I want to replace only the first occurrence.

The expected result is: "https://******:adss!#&@github.com/test/test.git" The actual result is: "https://#32$3:adss!#&@github.com/test/test.git"

Unfortunately it's not replaced. The code as bellow:

class Program
{
    private static Regex reg = new Regex(@"(?i)(http|https):\/\/(?<UserName>.*):(.*?)@.*\/");
    private const string userNameGroup = "UserName";

    static void Main(string[] args)
    {
        string url = matchRgexWithUserName("https://#32$3:adss!#&@github.com/test/test.git");

        Console.WriteLine(url);
    }

    static string matchRgexWithUserName(string url)
    {
        Match match = reg.Match(url.ToString());

        string username = match.Groups[userNameGroup].Value;
        Regex r = new Regex(username);
        url = r.Replace(url,"******",1);
        return url;
    }
}

this line works well:

string username = match.Groups[userNameGroup].Value;

the problem is with these lines:

Regex r = new Regex(username);
        url = r.Replace(url,"******",1);
        return url;

I suspect the problem is with the "$". Is there other way to overcome on it? Thanks!

Answer 1

It doesn't work, because $ is a special character in regex.

To solve the problem, you can put everything before UserName and after it into groups too:

Regex reg = new Regex(@"(?<firstPart>(?i)(http|https):\/\/)(?<UserName>.*)(?<secondPart>:(.*?)@.*\/)");

Then you can use Replace to combine firstPart , "******" and secondPart - without UserName :

string result = reg.Replace(url, "${firstPart}******${secondPart}");

Basically, you match the url to a {firstPart}{UserName}{secondPart} pattern and replace it with {firstPart}******{secondPart} (removing the UserName ).

Answer 2

Using Regex.Replace that way is the wrong way to go about this. Once you know the username, you can use a regular string replace:

url = url.Replace("://" + username, "://" + "*****");