title: CultureInfo on DateTime.ParseExact?
body: <p>I don't understand Why there is an overload with IFormatProvider in <code>DateTime.ParseExact</code> ? </p>
  
  <p>If I'm defining <strong>exactly</strong> how it should be parsed ( <em>spaces ,  separators etc</em>) , then theres should be no problem : </p>
  
  <p>All these 3 examples  show the same result: </p>
  
  <p><strong>example 1</strong>        </p>
  
  <pre><code>CultureInfo provider =CultureInfo.CreateSpecificCulture("en-US");
  var t=  DateTime.ParseExact("13-2-2013", "d-M-yyyy", provider, DateTimeStyles.None);  
  Console.WriteLine (t); //13/02/2013 00:00:00
  </code></pre>
  
  <p><strong>example 2</strong>        </p>
  
  <pre><code>  CultureInfo provider =CultureInfo.CreateSpecificCulture("en-US");
    var t=    DateTime.ParseExact("13/2/2013", "d/M/yyyy", provider, DateTimeStyles.None);  
    Console.WriteLine (t); //13/02/2013 00:00:00
  </code></pre>
  
  <p><strong>example 3</strong>   </p>
  
  <pre><code> CultureInfo provider =CultureInfo.CreateSpecificCulture("en-US");
  var t=  DateTime.ParseExact("13@@@2@@@2013", "d@@@M@@@yyyy", provider, DateTimeStyles.None);  
   Console.WriteLine (t); //13/02/2013 00:00:00
  </code></pre>
  
  <p>So why do i need to provide provider If I'm <strong>explicitly</strong> defining the structure ? </p>