title: PHP string to hex
body: <p>I have a string like that:</p>
  
  <pre><code>[0-9A-Za-z\+/=]*
  </code></pre>
  
  <p>How can I converted in the following form:</p>
  
  <pre><code>"\133\x30\55\x39\101\x2d\132\x61\55\x7a\134\x2b\57\x3d\135\x2a"
  </code></pre>
  
  <p>Is there any function for that ?</p>