生成随机数组-php

//1.生成随机数是用mt_rand()比rand()快
//2.去掉重复元素要更加简单用到 array_flip(array_flip())更快
//3.将数组的键重新进行赋值,使用shuffle()
//4.php7 开始完全要用mt_rand()替代rand()


function unique_rand($min, $max, $num) {
    $count = 0;
    $return = array();
    while ($count < $num) {
        $return[] = mt_rand($min, $max);
        $return = array_flip(array_flip($return));
        $count = count($return);
    }
    shuffle($return);
    return $return;
}