title: Combine two arrays
body: <p>I have two arrays like this:</p>
  
  <pre><code>array( 
  '11' =&gt; '11',
  '22' =&gt; '22',
  '33' =&gt; '33',
  '44' =&gt; '44'
  );
  
  array( 
  '44' =&gt; '44',
  '55' =&gt; '55',
  '66' =&gt; '66',
  '77' =&gt; '77'
  );
  </code></pre>
  
  <p>I want to combine these two array such that it does not contains duplicate and as well as keep their original keys. For example output should be:</p>
  
  <pre><code>array( 
  '11' =&gt; '11',
  '22' =&gt; '22',
  '33' =&gt; '33',
  '44' =&gt; '44',
  '55' =&gt; '55',
  '66' =&gt; '66',
  '77' =&gt; '77'
  );
  </code></pre>
  
  <p>I have tried this but it is changing their original keys:</p>
  
  <pre><code>$output = array_unique( array_merge( $array1 , $array2 ) );
  </code></pre>
  
  <p>Any solution?</p>