title: string.Format Input string was not in correct format for string with curly brackets already as part of the format C#
body: <p>I am trying to format a <code>Json</code> input to a <code>JSON RPC</code>. For example, the <code>JSON</code> am goint to post is as following,</p>
  
  <pre><code>"{"filter":{ "Ids": [123, 124], "Types":["EMPLOYEE"]}}"
  </code></pre>
  
  <p>which I expect to return users with id 123, 124 and of type EMPLOYEE. But for the Ids parameter, I want to may it dynamic so that I can set the value in my C# calling method like the following</p>
  
  <pre><code>string.Format("{\"filter\":{ \"Ids\": [{0}], \"Types\":[\"EMPLOYEE\"]}}", "123, 124");
  </code></pre>
  
  <p>when doing so, I get the format exception <code>"Input string was not in correct format"</code>....</p>
  
  <p>I know, I can build up the string using <code>string.concat</code> or <code>string builder</code>. Am just curious, if there is any solution to overcome this <code>string.format</code> exception in the event when a string has <code>curly brackets</code> (am assuming this is the cause of the exception) already.</p>