System.Net.WebException HTTP status code

(I do realise the question is old, but it's among the top hits on Google.)

A common situation where you want to know the response code is in exception handling. As of C# 7, you can use pattern matching to actually only enter the catch clause if the exception matches your predicate:

catch (WebException ex) when (ex.Response is HttpWebResponse response)
{
     doSomething(response.StatusCode)
}

This can easily be extended to further levels, such as in this case where the WebException was actually the inner exception of another (and we're only interested in 404):

catch (StorageException ex) when (ex.InnerException is WebException wex && wex.Response is HttpWebResponse r && r.StatusCode == HttpStatusCode.NotFound)

Finally: note how there's no need to re-throw the exception in the catch clause when it doesn't match your criteria, since we don't enter the clause in the first place with the above solution.