title: When is it better to use String.Format vs string concatenation?
body: <p>I've got a small piece of code that is parsing an index value to determine a cell input into Excel.  It's got me thinking...</p>
  
  <p>What's the difference between </p>
  
  <pre><code>xlsSheet.Write("C" + rowIndex.ToString(), null, title);
  </code></pre>
  
  <p>and</p>
  
  <pre><code>xlsSheet.Write(string.Format("C{0}", rowIndex), null, title);
  </code></pre>
  
  <p>Is one "better" than the other? And why?</p>