title: Display array_key from PHP array?
body: <p><strong>Here I am Having an Issue:</strong></p>
  
  <p>I have two arrays like the following:</p>
  
  <pre><code>  $array1 = array('1','2','1','3','1');
    $array2 = array('1','2','3'); // Unique $array1 values
  </code></pre>
  
  <p>with array2 values i need all keys of an array1</p>
  
  <p><strong>Expected Output Is:</strong></p>
  
  <pre><code> 1 =&gt; 0,2,4
   2 =&gt; 1
   3 =&gt; 3
  </code></pre>
  
  <p>here it indicates <code>array2 value</code> =><code>array1 keys</code></p>