(PHP 4, PHP 5, PHP 7)
mt_srand — Seeds the Mersenne Twister Random Number Generator
mt_srand ([ int $seed [, int $mode = MT_RAND_MT19937 ]] ) : void
Seeds the random number generator with seed
or with a random value if no seed
is given.
Note: There is no need to seed the random number generator with srand() or mt_srand() as this is done automatically.
seed
An arbitrary int seed value.
mode
Use one of the following constants to specify the implementation of the algorithm to use.
Constant | Description |
---|---|
MT_RAND_MT19937 | Uses the fixed, correct, Mersenne Twister implementation, available as of PHP 7.1.0. |
MT_RAND_PHP | Uses an incorrect Mersenne Twister implementation which was used as the default up till PHP 7.1.0. This mode is available for backward compatibility. |
No value is returned.
Version | Description |
---|---|
7.1.0 | srand() has been made an alias of mt_srand(). |
7.1.0 | mt_rand() has been updated to use the fixed, correct, version of the Mersenne Twister algorithm. To fall back to the old behaviour, use mt_srand() with MT_RAND_PHP as the second parameter. |
Example #1 mt_srand() example
<?php // seed with microseconds function make_seed() { list($usec, $sec) = explode(' ', microtime()); return $sec + $usec * 1000000; } mt_srand(make_seed()); $randval = mt_rand(); ?>
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https://www.php.net/manual/en/function.mt-srand.php