Port number retrieval

Question

For port number testing purpose I am passing the following URL, but it throws an exception, exception itself is null - no descriptive information

testURL = "ce-34-54-33.compute-1.amazonaws.com:";

Regex r = new Regex(@"^(?<proto>\w+)://[^/]+?:(?<port>\d+)?/",
RegexOptions.None, TimeSpan.FromMilliseconds(150));
// the following throws an exception
int port = Int32.Parse(r.Match(testURL).Result("${port}"));

Update:

If I use System.Uri, the value always -1 no matter whether or not I include port.

Uri uri = new Uri(connectionURL);
int value = uri.Port;

It throws an exception but the value of the exception is null? Are you sure? Is it being thrown by `new Regex`, `Match`, `Result`, or `Parse`? — Adrian, Jul 10 '17 at 20:35
The last line has 3 method calls in it. Which one is throwing the exception? — Adrian, Jul 10 '17 at 20:38
Screenshot doesn't show `null`. Maybe you get better result by manually catching? — , Jul 10 '17 at 20:51
I strongly believe what I have delivered is more than enough for SFO requirements. — casillas, Jul 10 '17 at 20:59
@hotspring however you didn't answer Adrian, Dmitry Bychenko or my comment. You still didn't state at all what is causing the error nor do you want to find out what error, nor do you proof Dmitry that you're wrong or right. — , Jul 10 '17 at 21:10
Dimitri has added his comment as an answer and deleted, because it does not work. — casillas, Jul 10 '17 at 21:15
If you check screenshot carefully, you will see issue of causing null (unable to evaluate the expression), but have no idea how to handle or what is causing this issue.If you have any idea, please provide. — casillas, Jul 10 '17 at 21:16
`testURL = "ce-34-54-33.compute-1.amazonaws.com:"` is it worth an answer that you forgot the `;`? — , Jul 10 '17 at 21:19
of course not :-), you cannot even compile the code, it is an error not exception! — casillas, Jul 10 '17 at 21:20

CodeCaster · Accepted Answer · 2017-07-10T21:26:16.620

The exception you get is:

System.NotSupportedException: 'Result cannot be called on a failed Match.'

Your testURL doesn't contain a port, so the named group "port" didn't match anything. It also doesn't contain a "proto", which isn't marked optional, so the entire regex has no matches. Finally, it doesn't end in the required slash.

So fix your input:

var testURL = "https://ce-34-54-33.compute-1.amazonaws.com:443/";

Regex r = new Regex(@"^(?<proto>\w+)://[^/]+?:(?<port>\d+)?/");

var port = int.Parse(r.Match(testURL).Result("${port}"));

And you'll see it works just fine.

Of course this code still needs additional error handling:

var testURL = "https://ce-34-54-33.compute-1.amazonaws.com:443/";

Regex r = new Regex(@"^(?<proto>\w+)://[^/]+?:(?<port>\d+)?/");

var match = r.Match(testURL);

var portGroup = match.Groups["port"];
int port = -1;

if (portGroup.Success)
{
    if (!int.TryParse(portGroup.Value, out port))
    {
        port = -1;
    }
}

This sets the port to -1 if none is present in the input URL.

`var testURL = "https://ce-34-54-33.compute-1.amazonaws.com:8` does not pick up the right port number, it still returns `{}` — casillas, Jul 10 '17 at 21:40
That's because the URL must end in a slash, as dictated by your regex. — CodeCaster, Jul 10 '17 at 21:40
Any idea for the following https://stackoverflow.com/questions/45022396/url-well-formed-returns-true-for-invalid-url — casillas, Jul 10 '17 at 22:07

Port number retrieval

1 Answers1