title: Intersection of two arrays of Strings in VBA
body: <p>This question might be a bit similar to this question but it is not.
  <a href="https://stackoverflow.com/questions/23683939/intersection-of-two-arrays-of-ranges">Intersection of two arrays of ranges</a></p>
  
  <p>Okay, I am currently working on a project with VBA and I need to filter a table.
  There are two filters looks like this (a1 and a2 contain strings for filter):</p>
  
  <pre><code>Dim a1() As String
  Dim a2() As String
  
  .Autofilter Field:=1, Criterial:=Array(a1)
  .Autofilter Field:=1, Criterial:=Array(a2)
  </code></pre>
  
  <p>So as you notice, the 2nd line of autofilter just overwrites, in a way, the previous filter and this is not the way I would like the filter to behave. I would like to have an array to have mutual elements of a1 and a2 so that I can filter with the mutual elements of two arrays.</p>
  
  <p>How would you intersect two arrays that contain couple of strings? I prefer not to use cells for this purpose just to reduce the worksheets on my workbook.</p>