\b(?<protocol>https?|ftp)://(?<domain>[-A-Z0-9.]+)(?<file>/[-A-Z0-9+&@#/%=~_|!:,.;]*)?(?<parameters>\?[-A-Z0-9+&@#/%=~_|!:,.;]*)?

string ResultString = null;
try {
  Regex RegexObj = new Regex("\\b(?<protocol>https?|ftp)://(?<domain>[-A-Z0-9.]+)(?<file>/[-A-Z0-9+&@#/%=~_|!:,.;]*)?(?<parameters>\\?[-A-Z0-9+&@#/%=~_|!:,.;]*)?",
    RegexOptions.IgnoreCase);
  ResultString = RegexObj.Match(SubjectString).Groups["groupname"].Value;
} catch (ArgumentException ex) {
  // Syntax error in the regular expression
}