How to write to a file line per line?

public static void Main()
{
        string path = @"c:\test.txt";
        if (!File.Exists(path))
        {
            // Create a file to write to.
            using (StreamWriter sw = File.CreateText(path))
            {
                sw.WriteLine("This");
                sw.WriteLine("code");
                sw.WriteLine("will");
                sw.WriteLine("write");
                sw.WriteLine("text");
                sw.WriteLine("per");
                sw.WriteLine("line");
            }
        }
}

string path = @"c:\test.rtf";
using (StreamWriter sw = File.CreateText(path))
{
   foreach (string line in  richTextBox1.Lines)
   {
      sw.WriteLine(line);
   }
}