in_array/array_key_exists等数组值查询效率分析

<?php

$arr = array();

$str = '';

for($i = 0; $i < 5000; $i++) {

       $a = 1000000000 + $i;

//      $str .= $a.",";

       $arr[$a] = $a;

}

$str = json_encode($arr);

$a = 1000001010;

for($j = 0; $j < 30000; $j++) {

/*if (preg_match("/{$a}/", $str)) {

       echo 'ok';

}*/

if (array_key_exists($a, $arr)) {

       echo 'ok';

}

/*if (in_array($a, $arr)) {

       echo 'ok';

}

if (isset($arr[$a])) {

       echo 'ok';

}*/

}

?>

今天分析了一下in_array,array_key_exists,isset,preg_match,array_search的效率

isset:

real    0m0.073s

user    0m0.028s

sys     0m0.044s

array_key_exists:

real    0m0.083s

user    0m0.036s

sys     0m0.047s

in_array:

real    0m1.664s

user    0m1.515s

sys     0m0.150s

array_search:

real    0m1.663s

user    0m1.534s

sys     0m0.129s

preg_match[根据要找的字符的位置时间会愈来愈长]:  

real    0m7.784s

user    0m7.673s

sys     0m0.111s

strpos[根据要找的字符的位置时间会愈来愈长]:  

real    0m2.689s

user    0m2.552s

sys     0m0.138s

json_decode,json_encode性能不好！30000个循环执行超长时间。最后本身中断了！