title: Index outside bounds of the array C#
body: <p>I'm trying to simplify a few long statements with arrays, I've found similar questions on here but I can't work out where i'm going wrong. The code is as follows: </p>
  
  <pre><code>if (coursechoice.Text == ("Subsidiary Diploma"))
  {               
      var grade = new[] { grade1, grade2, grade3, grade4, grade5, grade6, grade7, grade8, grade9, grade10, grade11, grade12, grade13, grade14, grade15, grade16, grade17, grade18 };
      var unitselect = new[] { unitselect1, unitselect2, unitselect3, unitselect4, unitselect5, unitselect6, unitselect7, unitselect8, unitselect9, unitselect10, unitselect11, unitselect12, unitselect13, unitselect15, unitselect16, unitselect17, unitselect18 };
  
  for (var i = 3; i &lt; 18; i++)
  {                   
      grade[i].Enabled = false;
      unitselect[i].Enabled = false; // I get index out of bounds of the array here
  }   
  </code></pre>
  
  <p>The code <code>grade[I].Enabled= false;</code> works fine, however its only the unitselect which doesn't work, thanks if you are able to help. </p>