mt_srand
(PHP 4, PHP 5)
mt_srand — Seed the better random number generator
Descrierea
void mt_srand
([ int $seed
] )
Seeds the random number generator with seed or with a random value if no seed is given.
Notă: Începând cu PHP 4.2.0 nu este nevoie de a însămânţa generatorul de numere aleatoare prin intermediul srand() sau mt_srand(), deoarece aceasta se efectuează în mod automat.
Parametri
- seed
-
An optional seed value
Istoria schimbărilor
| Versiunea | Descriere |
|---|---|
| Since 4.2.0 | The seed becomes optional and defaults to a random value if omitted. |
| Since 5.2.1 | The Mersenne Twister implementation in PHP now uses a new seeding algorithm by Richard Wagner. Identical seeds no longer produce the same sequence of values they did in previous versions. This behavior is not expected to change again, but it is considered unsafe to rely upon it nonetheless. |
Exemple
Example#1 mt_srand() example
<?php
// seed with microseconds
function make_seed()
{
list($usec, $sec) = explode(' ', microtime());
return (float) $sec + ((float) $usec * 100000);
}
mt_srand(make_seed());
$randval = mt_rand();
?>