title: How to hook into arithmetic operations in php extension
body: <p>I'm writing a PHP extension that overrides zend_execute_internal(), zend_execute_ex() and a few others hooks. But I cannot find out the way to hook into arithmetic/string operations at runtime. Is there any way to hook into the following code?</p>
  <pre><code>$x1 = '1111111111111111111111111111';
  $x2 = 'zzzzzzzzzzzzzzzzzzzzzzzzzzzz';
  $x3 = $x1 ^ $x2; // &lt;--- i need to handle this operation
  echo $x3 . &quot;\n&quot;;
  </code></pre>