URI error loading from txt file

Question

I'm having a problem with a basic piece of code:

var objReader = new StreamReader(ofDialog.FileName);
while (objReader.Peek() >= 0)
{
    Helpers.returnMessage(objReader.ReadLine());
    // trim the url to root
    var uri = new Uri(objReader.ReadLine());
    var host = uri.Host;
}

I'm loading a .txt file of urls, the trying to trim to root using uri.host but i'm getting the error:

Value cannot be null.Parameter name: UriString

But if i hard code a url in: var uri = new Uri("https://stackoverflow.com/questions/ask");

It works fine, it seems to be when i'm loading from a .txt file.

any help would be appreciated.

Complete code:

    private void btnInput_Click(object sender, EventArgs e)
    {
        // ofDialog settings
        ofDialog.Filter = @"TXT Files|*.txt";
        ofDialog.Title = @"Select your source backlink file...";
        ofDialog.FileName = "URLs.txt";

        // is cancel pressed?
        if (ofDialog.ShowDialog() == DialogResult.Cancel)
            return;
        try
        {
            var objReader = new StreamReader(ofDialog.FileName);
            while (objReader.Peek() >= 0)
            {
                //Helpers.returnMessage(objReader.ReadLine());
                // trim the url to root
                var x = objReader.ReadLine();
                Helpers.returnMessage(x);
                // trim the url to root
                var uri = new Uri(x);
                var host = uri.Host;

                //Helpers.returnMessage(host);

                // extract urls here
                var wc = new WebClient();
                var html = wc.DownloadString(objReader.ReadLine());

                // 1. Find all matches in file
                var m1 = Regex.Matches(html, @"(<a.*?>.*?</a>)",
                    RegexOptions.Singleline);

                // 2. Loop over each match
                foreach (Match m in m1)
                {
                    var value = m.Groups[1].Value;
                    string href;
                    // 3. Get href attribute
                    var m2 = Regex.Match(value, @"href=\""(.*?)\""",
                    RegexOptions.Singleline);
                    if (m2.Success)
                    {
                        href = m2.Groups[1].Value;
                    }
                    else
                    {
                        continue;
                    }

                    // add to the results
                    if (href.StartsWith("http"))
                    {
                        //Helpers.returnMessage(href);
                        if (!href.Contains(host)) 
                        {
                            // add urls to the listview
                            var lvi = new ListViewItem(href);
                            listViewMain.Items.Add(lvi);
                        }
                    }
                }
            }
        }
        catch (Exception ex)
        {
            Helpers.returnMessage(ex.Message);
        }
    }

returnMessage() literally just returns a message box popup.

Answer 1

Try this:

var objReader = new StreamReader(ofDialog.FileName);
while (objReader.Peek() >= 0)
{
   string x = objReader.ReadLine();
   Helpers.returnMessage(x);
  // trim the url to root
   var uri = new Uri(x);
   var host = uri.Host;
}