title: fastest way to get parent array key in multidimensional arrays with php
body: <p>what is the best way to get parent array key with multidimensional arrays?
  for example I have this array:</p>
  
  <pre><code>array(
  
      [0] =&gt; array(0=&gt; sample, 1=&gt;picture, 2=&gt;frame, 3=&gt;google)
  
      [1] =&gt; array(0=&gt; iphone, 1=&gt;orange, 2=&gt;love, 3=&gt;msn)
  
      [2] =&gt; array(0=&gt; joe, 1=&gt;geee, 2=&gt;panda, 3=&gt;yahoo)
  )
  </code></pre>
  
  <p>now I need to search for example google and get the parent array key..
  which it should be 0...any ideas? I used for loop for this but I think it will be slow if I have arrays with 700000 rows..</p>