Random\Engine\Mt19937::__construct

(PHP 8 >= 8.2.0)

Random\Engine\Mt19937::__construct — Constructs a new Mt19937 engine

说明

public Random\Engine\Mt19937::__construct(?int $seed = null, int $mode = MT_RAND_MT19937)

警告

由于 Mt19937（“梅森旋转算法”）引擎仅接受 32 位整数作为种子，因此尽管 Mt19937 的范围为 2¹⁹⁹³⁷-1，但可能的随机序列数量仅限于 2³²（即 4,294,967,296）。

当依赖隐式或显式随机播种时，重复会出现得更早。根据生日问题，在少于 80,000 个随机生成的种子后，预计重复种子的概率为 50%。在随机生成大约 30,000 个种子后，重复种子的概率为 10%。

This makes Mt19937 unsuitable for applications where duplicated sequences must not happen with more than a negligible probability. 如果需要可重复的种子，Random\Engine\Xoshiro256StarStar 和 Random\Engine\PcgOneseq128XslRr64 引擎都支持更大的种子，它们不太可能随机碰撞。如果不需要再现性，Random\Engine\Secure 引擎提供加密安全随机性。

参数

seed

Fills the state with values generated with a linear congruential generator that was seeded with seed interpreted as an unsigned 32 bit integer.

If seed is omitted or null, a random unsigned 32 bit integer will be used.

mode

Use one of the following constants to specify the implementation of the algorithm to use.

MT_RAND_MT19937: The correct Mt19937 implementation.
MT_RAND_PHP: An incorrect implementation for backwards compatibility with mt_srand() prior to PHP 7.1.0.

警告

本特性已自 PHP 8.3.0 起废弃。强烈建议不要使用本特性。

示例

示例 #1 Random\Engine\Mt19937::__construct() example

<?php
// Uses a random 32 Bit seed.
$e = new \Random\Engine\Mt19937();

$r = new \Random\Randomizer($e);
?>