php生成400个不重复的16位随机数
需求是：php生成400个不重复的16位随机数，装进数组
function str_rand()
{
$str = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
$str = "___".substr(str_shuffle($str),0,16);
return $str;
}
$arr = [];
while(count($arr) < 400)
{
$tmp = str_rand();
$arr[$tmp] = $tmp;
}
var_dump(array_keys($arr));