Why does a function return a reference that is slower than the return value? Why is writing a copy slower than a quote?

$array = range(1, 10000);function test1($array){    return $array;}function &test2($array){    return $array;}$start = microtime(true);for ($i=0; $i < 10000; $i++) {     $arr = test1($array);    $arr[$i] = 'new';}$end = microtime(true);echo "Cost ".($end - $start)."\n";$start = microtime(true);for ($i=0; $i < 10000; $i++) {     $arr = test2($array);    $arr[$i] = 'new';}$end = microtime(true);echo "Cost ".($end - $start)."\n";

Output Result:
Cost 5.5163149833679
Cost 6.3323628902435
Although the gap is not big

Reply content:

$array = range(1, 10000);function test1($array){    return $array;}function &test2($array){    return $array;}$start = microtime(true);for ($i=0; $i < 10000; $i++) {     $arr = test1($array);    $arr[$i] = 'new';}$end = microtime(true);echo "Cost ".($end - $start)."\n";$start = microtime(true);for ($i=0; $i < 10000; $i++) {     $arr = test2($array);    $arr[$i] = 'new';}$end = microtime(true);echo "Cost ".($end - $start)."\n";

Output Result:
Cost 5.5163149833679
Cost 6.3323628902435
Although the gap is not big

The copy needs to open up space for initialization and so on, equivalent to creating several new objects.
And a reference is just a pointer.

First, according to the PHP: reference return-Manual explanation, the above two kinds of writing is no different, you can understand that the function without & the underlying engine will be optimized, so it may indeed be a little bit faster, so the manual is not recommended.

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