title: Substitute all non matching characters between certain columns
body: <p>I'm trying to substitute all <strong>non matching</strong> characters in a single line between certain columns (after a search).</p>
  
  <p><em><strong>Example</em></strong>:<br>
  The search can be everything<br>
  In example below the search = <code>test</code><br>
  The substitute character of non matching characters: empty space.</p>
  
  <p>I want to substitute all characters non part of "<code>test</code>" <em>between columns 10 and 30</em>.<br>
  Columns 10 and 30 are indicated with <code>|</code></p>
  
  <pre><code>before:  djd&lt;aj.testjal.kjetestjaja testlala ratesttsuvtesta !&lt;-a-
                    |                   |   
  after:   djd&lt;aj.test       test     testlala ratesttsuvtesta !&lt;-a-
  </code></pre>
  
  <p>How can I realize this?</p>