mt_srand
(PHP 4, PHP 5)
mt_srand — Seed the better random number generator
Description
void mt_srand
([ int $seed
] )
Seeds the random number generator with seed or with a random value if no seed is given.
Note: מאז PHP 4.2.0, אין שום צורך להשתמש במחולל מספרים אקראיים בעזרת srand() או בעזרת mt_srand() משום שמכשיו זה נעשה אוטומטית.
Parameters
- seed
-
An optional seed value
ChangeLog
Version | Description |
---|---|
Since 4.2.0 | The seed becomes optional and defaults to a random value if omitted. |
Since 5.2.1 | The Mersenne Twister implementation in PHP now uses a new seeding algorithm by Richard Wagner. Identical seeds no longer produce the same sequence of values they did in previous versions. This behavior is not expected to change again, but it is considered unsafe to rely upon it nonetheless. |
דוגמאות
Example#1 mt_srand() example
<?php
// seed with microseconds
function make_seed()
{
list($usec, $sec) = explode(' ', microtime());
return (float) $sec + ((float) $usec * 100000);
}
mt_srand(make_seed());
$randval = mt_rand();
?>