(PHP 4, PHP 5, PHP 7, PHP 8)
mt_srand — 播下一個(gè)更好的隨機數發(fā)生器種子
$seed = ?): void
用
seed 來(lái)給隨機數發(fā)生器播種。 沒(méi)有設定 seed 參數時(shí)，會(huì )被設為隨時(shí)數。
注意: 不再需要用 srand() 或 mt_srand() 給隨機數發(fā)生器播種，因為現在是由系統自動(dòng)完成的。
seed可選的種子值
沒(méi)有返回值。
| 版本 | 說(shuō)明 |
|---|---|
| 4.2.0 |
The seed becomes optional
and defaults to a random value if omitted.
|
| 5.2.1 | The Mersenne Twister implementation in PHP now uses a new seeding algorithm by Richard Wagner. Identical seeds no longer produce the same sequence of values they did in previous versions. This behavior is not expected to change again, but it is considered unsafe to rely upon it nonetheless. |
示例 #1 mt_srand() 例子
<?php
// seed with microseconds
function make_seed()
{
list($usec, $sec) = explode(' ', microtime());
return (float) $sec + ((float) $usec * 100000);
}
mt_srand(make_seed());
$randval = mt_rand();
?>