如何快速判断一个值是否在数组中

?php$s = '';for($i=1;$i=1000000;$i ){$r = rand(1000000,9999999);$s .= $r.',';}$a = explode(',',$s);$t1 =microtime(true);for($i=0;$i100;$i ){$t = rand(1,1000000);if(in_array($a[$t],$a)){}}$t2 = microtime(true);$b = array_flip($a);for($i=0

<?php
$s = '';
for($i=1;$i<=1000000;$i++){
$r = rand(1000000,9999999);
$s .= $r.',';
}
$a = explode(',',$s);
$t1 =microtime(true);
for($i=0;$i<100;$i++){
$t = rand(1,1000000);
if(in_array($a[$t],$a)){}
}
$t2 = microtime(true);
$b = array_flip($a);
for($i=0;$i<100;$i++){
$t = rand(1,1000000);
if(isset($a[$t],$b)){}
}
$t3 = microtime(true);
$c = array_flip($a);
for($i=0;$i<100;$i++){
$t = rand(1,1000000);
if(array_key_exists($a[$t],$c)){}
}
$t4 = microtime(true);
echo $t2-$t1;
echo "\r\n";
echo $t3-$t2;
echo "\r\n";
echo $t4-$t3;
echo "\r\n";

time php -f test.php 运行结果如下

8.6652669906616
0.43561315536499
0.67533493041992

real?? ?0m14.255s
user?? ?0m11.990s
sys?? ?0m0.380s

原文地址：如何快速判断一个值是否在数组中, 感谢原作者分享。