title: Concatenate dictionary keys separated by comma's
body: <p>I'm looking for a better way to concatenate dictionary keys, this is what I'm doing now :</p>
  
  <pre><code>Dictionary&lt;int, string&gt; myList = new Dictionary&lt;int, string&gt;();
  
  myList.Add(1, "value");
  myList.Add(2, "value");
  myList.Add(3, "value");
  myList.Add(4, "value");
  
  string choices = "";
  
  foreach (int key in myList.Keys)
  {
      choices += key + " ";
  }
  
  choices = "(" + choices.Trim().Replace(" ", ",") + ")"; // (1,2,3,4)
  </code></pre>
  
  <p>I'm sure there is a better way, with LINQ maybe ?</p>