Hello everyone
in version the 5.2.1 i get strange results when using the reference
operator on arrays. When writing a function "a" with call by reference:
function &a(&$anArray) { return $anArray; }
and another function "b":
function b($anArray) { return $anArray; }
Then on my machine it takes much longer to call function "a" than to call
function "b". Actually it seems that function "a" always copies the hole
array wheter or not i write to it - while function "b" does not copy that
array as long as i only read from it.
But why does function "a" copy at all? Has anyone a explanation?
Here is the benchmark code which shows the speed difference:
<?php
echo phpversion()."\n";
echo "test1\ttest2\n";
function a($p){return $p;}
function &b(&$p){return $p;}
$test1 = $test2 = array();
for ($i = 0;$i < 10000;$i++) {$test_array[] = $i;}
$repeat = 10;
for($j=0;$j<$repeat;$j++)
{
$start_time = microtime(true);
for ($i=0;$i<500;$i++) {
$x = a($test_array);
$x[0];
}
$execution_time = microtime(true) - $start_time;
echo number_format($execution_time,4)."\t";
$test1[] = $execution_time;
$start_time = microtime(true);
$count = count($test_array);
for ($i=0;$i<500;$i++) {
$x = b($test_array);
$x[0];
}
$execution_time = microtime(true) - $start_time;
echo number_format($execution_time,4)."\n";
$test2[] = $execution_time;
}
echo "==============\n";
echo number_format(array_sum($test1)/$repeat,4)."\t";
echo number_format(array_sum($test2)/$repeat,4)."\n";
?>
Output on my machine:
5.2.1
test1 test2
0.0004 0.8020
0.0004 0.7862
0.0004 0.7970
0.0004 0.7752
0.0004 0.7783
0.0004 0.7797
0.0004 0.7834
0.0004 0.7806
0.0004 0.7747
0.0004 0.7777
==============
0.0004 0.7835
