How can I fix the loop so that it only adds one transition (Loop + regex)?

Question

C++ / C#

I have a text file, I wrote an algorithm using a loop that searches for text between double quotes on each line, writes it to a richtextbox in a column, but when it does not find text between "tags", it makes a transition. How to avoid it?

if (ofd.ShowDialog()== DialogResult.OK)
            {
                StreamReader sr = new StreamReader(ofd.FileName);
                string line = sr.ReadLine();
                string id = "(?<=\")(.*)(?=\")";
                while (line !=null)
                {
                    var match = Regex.Match(line, id );
                    Storage.AppendText(match.ToString());
                    line = sr.ReadLine();
                }
                sr.Close();
            }

Answer 1

if (!string.IsNullOrEmpty(match.ToString())
   Storage.AppendText(match.ToString());