title: PHP explode() function issue
body: <p>Please help me out on this explode() function issue. I am getting unexpected results for the third scenario, what's the explanation?</p>
  
  <p><strong>EDIT:</strong> The value $page_string is actually from the database. This time I did the tests using var_dump instead of echo. The strings, How does php count them? How is "15&amp;page" count 11?</p>
  
  <pre><code>var_dump($page_string);//string(11) "15&amp;page"
  </code></pre>
  
  <p><strong>1.</strong> Pop out ampersand ... fine. </p>
  
  <pre><code>    $page_id_array = explode("&amp;",$page_string);
      $page_id = $page_id_array[0]; 
      var_dump($page_id); 
      // string(2) "15"
  </code></pre>
  
  <p><strong>2.</strong> Pop out number ... fine</p>
  
  <pre><code>    $page_id_array = explode("15",$page_string);
      $page_id = $page_id_array[1]; 
      var_dump($page_id); 
      //string(9) "&amp;blog"
  </code></pre>
  
  <p><strong>3.</strong> Pop out '&amp;page' ... why?</p>
  
  <pre><code>     $page_id_array = explode("&amp;page",$page_string);
       $page_id = $page_id_array[0]; 
       var_dump($page_id); 
       //string(11) "15&amp;page"
       var_dump($page_id_array[1]);
       //NULL
  </code></pre>
  
  <p><strong>EDIT:</strong> After answer and comments from jasonbar I did the test which confirms his answer:</p>
  
  <pre><code>     $page_id_array = explode("&amp;amp;page",$page_string);
       $page_id = $page_id_array[0]; 
       var_dump($page_id); 
       //string(2) "15"
  </code></pre>