srand
(PHP 4, PHP 5)
srand — Seed the random number generator
Description
void srand
([ int $seed
] )
Seeds the random number generator with seed or with a random value if no seed is given.
Note: 由PHP 4.2.0 始，您不需要再使用 srand() 或 mt_srand() 為亂數產生器提供種子，因為這已自動的提供了。
Parameters
- seed
-
Optional seed value
ChangeLog
| Version | Description |
|---|---|
| Since 4.2.0 | The seed becomes optional and defaults to a random value if omitted. |
範例
Example#1 srand() example
<?php
// seed with microseconds
function make_seed()
{
list($usec, $sec) = explode(' ', microtime());
return (float) $sec + ((float) $usec * 100000);
}
srand(make_seed());
$randval = rand();
?>