两个大数组foreach，找出相同的key数量，所用的时间对比

<?phpfunction microtime_float() {list($usec, $sec) = explode(" ", microtime());return ((float)$usec + (float)$sec);}for($i = 1;$i <= 10000;$i++) {$data_1[$i] = 1;}for($i = 1001;$i <= 600000;$i++) {$data_2[$i] = 1;}$time_start = microtime_float();$num = 0;foreach ($data_1 as $key => $value) {if ($data_2[$key]) {$num++;}}echo $num;$time_end = microtime_float();$delta_time = $time_end - $time_start;echo '程序总用时：'.round($delta_time, 3).'秒。';$time_start = microtime_float();$num = 0;foreach ($data_2 as $key => $value) {if ($data_1[$key]) {$num++;}}echo $num;$time_end = microtime_float();$delta_time = $time_end - $time_start;echo '程序总用时：'.round($delta_time, 3).'秒。';?>

结果：9000程序总用时：0.003秒。9000程序总用时：0.595秒。

foreach放小的数组，速度比较快。