Error in calculating difference between two Unix timestamp in php
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I have a function which calculate the difference between two timestamps,

    public static function getDuration($from, $to) {
        $duration = $to - $from; 
        return $duration;
    }

but this is not working as required.
example, if i pass,
 

   

    $difference = getDuration(strtotime('19-07-2012 23:00:00'), strtotime('20-07-2012 4:45:00'));
    echo $difference/3600;

it returns 5.75 instead of 5.45, when converted to hours.