title: C# String.Format optional parameters
body: <p>I want to use <code>string.Format</code> with <code>optional parameters</code> :</p>
  
  <pre><code>public static void Main(string[] args)
  {
      // Your code goes here
      // Console.WriteLine(string.Format("{0} {1}", "a", "b"));
      Console.WriteLine(string.Format("{0} {1}", "a"));
  }
  </code></pre>
  
  <p>for exemple the parameter <code>{1}</code> to be optional and to have a default value </p>
  
  <p>Can you help me to do this?</p>