title: replace a string within a range in C#
body: <p>I have a string, myString, that is about 10000 in length.</p>
  
  <p>If I do <code>myString.Replace("A","B");</code> It will replace all instances of A to B.</p>
  
  <p>How can I do that not to the entire string but only to character 5000-5500?</p>