title: Is array_merge perform reindexing?
body: <p>Suppose I have an associative array with keys that are alphabetic string, and if I merge something to this array, It will merge successfully without reindexing like</p>
  
  <pre><code>$arr1 = array('john'=&gt;'JOHN', 'marry'=&gt;'Marry');
  $arr1 = array_merge(array('78'=&gt;'Angela'),$arr1);
  print_r($arr1);
  </code></pre>
  
  <p>then this will correctly merge new component to array and its output will be</p>
  
  <pre><code>Array
  (
      [0] =&gt; Angela
      [john] =&gt; JOHN
      [marry] =&gt; Marry
  )
  </code></pre>
  
  <p>But when I tried same thing like this</p>
  
  <pre><code> $arr1 = array('34'=&gt;'JOHN', '04'=&gt;'Marry');
   $arr1 = array_merge(array('78'=&gt;'Angela'),$arr1);
   print_r($arr1);
  </code></pre>
  
  <p>then its output is like this</p>
  
  <pre><code>Array
  (
      [0] =&gt; Angela
      [1] =&gt; JOHN
      [04] =&gt; Marry
  )
  </code></pre>
  
  <p>Can anyone describes this scenario.....
  Also I want my array to be like this after merging..</p>
  
  <pre><code>Array
      (
          [78] =&gt; Angela
          [34] =&gt; JOHN
          [04] =&gt; Marry
      )
  </code></pre>
  
  <p>How can I Achieve that??</p>