title: How to check whether a string is a valid HTTP URL?
body: <p>There are the <a href="https://msdn.microsoft.com/en-us/library/system.uri.iswellformeduristring(v=vs.110).aspx" rel="noreferrer"><code>Uri.IsWellFormedUriString</code></a> and <a href="http://msdn.microsoft.com/en-us/library/ms131572.aspx" rel="noreferrer"><code>Uri.TryCreate</code></a> methods, but they seem to return <code>true</code> for file paths, etc.</p>
  <p>How do I check whether a string is a valid (not necessarily active) HTTP URL for input validation purposes?</p>