title: how to serialize array as url queryString in php?
body: <p>I need to convert an array such as this:</p>
  
  <pre><code>$arr = array(1, 2, 3) ; 
  </code></pre>
  
  <p>to this format:</p>
  
  <pre><code>arr[0]=1&amp;arr[1]=2&amp;arr[2]=3
  </code></pre>
  
  <p>is there any built in function in php or i must create this my self?</p>