title: Produce a round-trip string for a decimal type
body: <p>If I wanted to convert a <em>double</em> to a <em>string</em> and back to a <em>double</em> that matches exactly, I would use something like:</p>
  
  <pre><code>double d1 = 1 / 3.0;
  string s = d1.ToString("R");
  double d2 = double.Parse(s);
  </code></pre>
  
  <p>But, the "R" format isn't defined for a <em>decimal</em> type (you get a "FormatException: Format specifier was invalid").</p>
  
  <p>What is the way to produce a round-trip string for a decimal type?</p>