title: code igniter / php - concatenating two POST variables to form a new variable
body: <p>I have a form where a user submits his member name, first and last. I want to combine these two and send them to the database as a member ID using code igniter's <code>url_title</code> functionality. In other words just making sure that it's all lower case, underscores, URL safe, etc. This is the code in my model, but in the database I'm getting a value of zero for the <code>memberID</code>:</p>
  
  <pre><code>$v_membername = $this-&gt;input-&gt;post('f_membername');
  $v_memberlast = $this-&gt;input-&gt;post('f_memberlast');
  $v_memberid = $v_membername + "_" + $v_memberlast;
  $v_memberid = url_title($v_memberid, 'underscore');
  
  $data = array(
      'member_name' =&gt; $v_membername,
      'member_last' =&gt; $v_memberlast,
      'member_id' =&gt; $v_memberid
  );
  
  $this-&gt;db-&gt;insert('members', $data);
  </code></pre>
  
  <p>Any idea what I'm doing wrong here? <code>membername</code> and <code>memberlast</code> submit to the DB just fine.</p>