PHP的随机播放功能随机性如何？

shuffle()

srand()

mtrand()

function mt_shuffle($array) {
    $randArr = [];
    $arrLength = count($array);

    // while my array is not empty I select a random position
    while (count($array)) {
        //mt_rand returns a random number between two values
        $randPos = mt_rand(0, --$arrLength);
        $randArr[] = $array[$randPos];

        /* If number of remaining elements in the array is the same as the
         * random position, take out the item in that position,
         * else use the negative offset.
         * This will prevent array_splice removing the last item.
         */
        array_splice($array, $randPos, ($randPos == $arrLength ? 1 : $randPos - $arrLength));
    }

    return $randArr;
}

shuffle

mt_rand

mt_srand

rand

rand

srand

mt_

rand()

mt_rand()

shuffle()

mt_strand()

function mt_shuffle_array($array) {
    $shuffled_array = [];
    $arr_length = count($array);

    if($arr_length < 2) {
        return $array;
    }

    while($arr_length) {
        --$arr_length;
        $rand_key = array_keys($array)[mt_rand(0, $arr_length)];

        $shuffled_array[$rand_key] = $array[$rand_key];
        unset($array[$rand_key]);
    }

    return $shuffled_array;
}

$array = [-2, -1, \'a\' => \'1\', \'b\' => \'2\', \'c\' => \'3\', 11, \'d\' => \'4\', 22];
$shuffled_array = mt_shuffle_array($array);

/**
 * Build a random array
 *
 * @param mixed $array
 *
 * @return array
 */
function random_array($array) {
    $random_array = array();
    // array start by index 0
    $countArray = count($array) - 1;

    // while my array is not empty I build a random value
    while (count($array) != 0) {
        //mt_rand return a random number between two value 
        $randomValue = mt_rand(0, $countArray);
        $random_array[] = $array[$randomValue];

        // If my count of my tab is 4 and mt_rand give me the last element, 
        // array_splice will not unset the last item
        if(($randomValue + 1) == count($array)) {
            array_splice($array, $randomValue, ($randomValue - $countArray + 1));
        } else {
            array_splice($array, $randomValue, ($randomValue - $countArray));
        }

        $countArray--;
    }

    return $random_array;
}