title: IEnumerable<char> to string
body: <p>I've never stumbled across this before, but I have now and am surprised that I can't find a really easy way to convert an <code>IEnumerable&lt;char&gt;</code> to a <code>string</code>.</p>
  
  <p>The best way I can think of is <code>string str = new string(myEnumerable.ToArray());</code>, but, to me, it seems like this would create a new <code>char[]</code>, and then create a new <code>string</code> from that, which seems expensive.</p>
  
  <p>I would've thought this would be common functionality built into the .NET framework somewhere. Is there a simpler way to do this?</p>
  
  <p>For those interested, the reason I'd like to use this is to use LINQ to filter strings:</p>
  
  <pre><code>string allowedString = new string(inputString.Where(c =&gt; allowedChars.Contains(c)).ToArray());
  </code></pre>