mt_srand
(PHP 4, PHP 5)
mt_srand — Seed the better random number generator
Popis
void mt_srand
([ int $seed
] )
Seeds the random number generator with seed or with a random value if no seed is given.
Note: Počínajúc PHP 4.2.0 nie je potrebné štartovať generátor náhodných čísel s srand() alebo mt_srand(), nakoľko sa tak učiní automaticky.
Parametre
- seed
-
An optional seed value
ChangeLog
| Verzia | Popis |
|---|---|
| Since 4.2.0 | The seed becomes optional and defaults to a random value if omitted. |
| Since 5.2.1 | The Mersenne Twister implementation in PHP now uses a new seeding algorithm by Richard Wagner. Identical seeds no longer produce the same sequence of values they did in previous versions. This behavior is not expected to change again, but it is considered unsafe to rely upon it nonetheless. |
Príklady
Example#1 mt_srand() example
<?php
// seed with microseconds
function make_seed()
{
list($usec, $sec) = explode(' ', microtime());
return (float) $sec + ((float) $usec * 100000);
}
mt_srand(make_seed());
$randval = mt_rand();
?>