Quick code snippet today. Let's say you have some URLs that you want to change the hostname/port on it without having to do string manipulation.

//multiple constructor are available
        UriBuilder builder = new UriBuilder("http://localhost:1712")
        {
        Host = Environment.MachineName,
        Port = 80
        };
        Uri myNewUri = builder.Uri; 

There you go! It's as easy as this. This will avoid countless hour of parsing a URL for the hostname, port number or whatever else you are searching.

The bonus with that is that the path of the URL won't be touched at all.

Have fun!