title: PHP - Usort returns 1 instead array
body: <p>I have multidimensional array that i want to sort by field containing unix timestamp:</p>
  
  <pre><code> Array ( 
  [0] =&gt; Array ( [0] =&gt; 723 [1] =&gt; 1442008738 ) 
  [1] =&gt; Array ( [0] =&gt; 721 [1] =&gt; 1386802800 ) 
  [2] =&gt; Array ( [0] =&gt; 718 [1] =&gt; 1356994800 ) 
  
  ) 
  </code></pre>
  
  <p>But when i use Usort, it just returns 1. What am i doing wrong?</p>
  
  <pre><code>function date_compare($a, $b)
  {
      $t1 = $a[1];
  
      $t2 = $b[1];
      return $t1 - $t2;
  }    
  print_r(usort($dosortowania2, 'date_compare'));
  </code></pre>