title: PHP: add missing keys between arrays
body: <p>I have following array keys values:</p>
  
  <pre><code>$arrData = array
  (
      array(
          'a' =&gt; 'test',
          'c' =&gt; 1,
          'd' =&gt; 2,
          'e' =&gt; 'B'
      ),
      array(
          'c' =&gt; 1,
          'd' =&gt; 2,
          'e' =&gt; 'B'
      ),
      array(
          'b' =&gt; 'test2',
          'c' =&gt; 1,
          'd' =&gt; 2,
          'e' =&gt; 'B'
      )
  );
  </code></pre>
  
  <p>So here I need to merged array into single with combining missing keys with single value array.
  Can someone please help to get following output in single array?</p>
  
  <pre><code>$arrData = array
  (
      array(
          'a' =&gt; 'test',
          'b' =&gt; 'test2',
          'c' =&gt; 1,
          'd' =&gt; 2,
          'e' =&gt; 'B'
      )
  );
  </code></pre>
  
  <p>Thanking in advance!</p>