Reformatting extracted substrings using Match.Result in C# .NET
January 3, 2017 2 Comments
Say you have the following Uri:
http://localhost:8080/webapps/bestapp
…and you’d like to extract the protocol and the port number and concatenate them. One option is a combination of a regular expression and matching groups within the regex:
private static void ReformatSubStringsFromUri(string uri)
{
Regex regex = new Regex(@"^(?<protocol>\w+)://[^/]+?(?<port>:\d+)?/");
Match match = regex.Match(uri);
if (match.Success)
{
Console.WriteLine(match.Result("${protocol}${port}"));
}
}
The groups are defined by “protocol” and “port” and are referred to in the Result method. The result method is used to reformat the extracted groups, i.e the substrings. In this case we just concatenate them. Calling this method with the URL in above yields “http:8080”.
However you can a more descriptive string format, e.g.:
Console.WriteLine(match.Result("Protocol: ${protocol}, port: ${port}"));
…which prints “Protocol: http, port: :8080”.
View all posts related to string and text operations here.
About Andras Nemes
Exercises in .NET with Andras Nemes 
Your daily tips are highly appreciated. I personally use Regexes a lot. However, most people hate them because they tend to become hard to read. In such cases, using the `RegexOptions.IgnorePatternWhitespace` option might help. The above method could be reformatted like this:
private static void ReformatSubStringsFromUri(string uri) { Regex regex = new Regex(@" ^ (?<protocol>\w+): # eg. http: //[^/]+? # host name or IP (?<port>:\d+)? # optional numeric port / # path ", RegexOptions.IgnorePatternWhitespace ); Match match = regex.Match(uri); if (match.Success) { Console.WriteLine(match.Result("Proto: ${protocol}, Port: ${port}")); } }Best,
Wolfgang
Thanks for your input!