title: First split then join a subset of a string
body: <p>I have an input string as follows:</p>
  
  <pre class="lang-none prettyprint-override"><code>thumb_634735515600845357tchayat_november_200612.jpg
  </code></pre>
  
  <p>What I want to do is first <em>split</em> this string by <code>_</code>. And then take the resulting tokens at positions 1 to n and <em>join</em> them.</p>
  
  <p>Specifically, with respect to my sample input, here is my desired output. As you can see, <code>thumb_</code> has been removed from the front of the string:</p>
  
  <pre class="lang-none prettyprint-override"><code>634735515600845357tchayat_november_200612.jpg
  </code></pre>
  
  <p>I know how to do the split. But then how do I do the join step that follows? I do realize that I can use a <code>for</code> loop to do the join. But is there a better way? I can't use a sub-string approach to do the join step because I have data before <code>thumb_</code>.</p>
  
  <p>Finally, note that the <code>_</code> character that follows <code>thumb</code> is always the first instance of <code>_</code>.</p>