title: Coalesce vs empty string concatenation
body: <p>My coworker is new to C# and didn't know about the coalesce operator.  So, I saw him write a line of code like this:</p>
  
  <pre><code>string foo = "" + str;
  </code></pre>
  
  <p>The idea being that if str is null, this expression would return an empty string.  Of course, that could be rewritten as this:</p>
  
  <pre><code>string foo = str ?? "";
  </code></pre>
  
  <p>And I feel that would be more readable.  But is it really that big a deal?  Are the readability benefits enough to suggest going back and making those lines look like the second?  Or is this one of those things that I should learn to let go (provided that my coworker is educated on the best way to do this in the future)?</p>
  
  <p><strong>EDIT</strong>:  Just a note, I appreciate the efficiency comments, but this isn't really being used in any situations where that performance would be critical.  So while that info is interesting, it's not necessarily what I feel is important.</p>