title: C#: Splicing array
body: <p>Let's say I have a <code>long[]</code> called <code>IDs</code> with a few elements in the array. </p>
  
  <p>What's the easiest way to splice into/insert a new element at a given index?</p>
  
  <p>Right now I'm doing this, and I don't think it's optimal:</p>
  
  <pre><code>long[] IDs = ...;
  
  var IDsList = IDs.ToList();
  IDsList.Insert(newId, indexToInsertAt);
  
  IDs = IDsList.ToArray();
  </code></pre>
  
  <p>There's nothing built-in into the <code>Array</code> class?! This strikes me as very odd, coming from the JavaScript world of <code>[].splice()</code>.</p>