note 68949 added to function.array-unique

In response to muddmonkey's flip-flip method, i would like to note that using this method as-is leaves the array with gaps. For example, if we have an array like this: Array ( [0] => 1 [1] => 1 [2] => 1 ) And you apply the flip-flip method, you get this: Array ( [2] => 1 ) If you apply the array_merge function to the result, it closes these gaps without seriously sacrificing performance. I wrote some test code that would result in a unique array that has 10,000 elements so that the impact of array_merge was more evident. Here is my test code: function microtime_float(){ //timing (stolen from muddmonkey) list($usec, $sec) = explode(" ", microtime()); return ((float)$usec + (float)$sec); } //make an array and fill it up $final=array(); for($i=0;$i<50000;$i++){ $final[]=$i%10000; //make sure the unique array has 10000 elements } //try flip-flip $start1 = microtime_float(); array_flip(array_flip($final)); $stop1=microtime_float(); echo($stop1-$start1.' (flip-flip)<br>'); //try my flip-flip-merge $start2=microtime_float(); array_merge(array_flip(array_flip($final))); $stop2=microtime_float(); echo($stop2-$start2.' (flip-flip-merge)<br />'); //try array_unique $start3=microtime_float(); array_unique($final); $stop3=microtime_float(); echo($stop3-$start3.' (array_unique)<br />'); Here was the result: 0.14240193367004 (flip-flip) 0.18947601318359 (flip-flip-merge) 3.7108051776886 (array_unique) As you can see, flip-flip-merge slows it down a little, but both are still way faster than array_unique. ---- Server IP: 216.194.113.175 Probable Submitter: 132.170.4.82 ---- X-Spam-Status: No, hits=3.3 required=5.0 tests=DATE_MISSING,FROM_NO_LOWER, HTML_MESSAGE autolearn=no version=2.64 ---- Manual Page -- http://www.php.net/manual/en/function.array-unique.php Edit -- https://master.php.net/note/edit/68949 Del: integrated -- https://master.php.net/note/delete/68949/integrated Del: useless -- https://master.php.net/note/delete/68949/useless Del: bad code -- https://master.php.net/note/delete/68949/bad+code Del: spam -- https://master.php.net/note/delete/68949/spam Del: non-english -- https://master.php.net/note/delete/68949/non-english Del: in docs -- https://master.php.net/note/delete/68949/in+docs Del: other reasons-- https://master.php.net/note/delete/68949 Reject -- https://master.php.net/note/reject/68949 Search -- https://master.php.net/manage/user-notes.php