PHP srand() Function
The PHP srand() function is used to seed the random number generator with seed or with a random value if no seed is given.
Please note that there is no need to seed the random number generator with srand() or mt_srand() as this is done automatically.
Syntax
srand(seed)
Parameters
seed |
Optional. Specify an int seed value. |
Return Value
None.
Example:
In the example below, srand() function is used to seed the random number generator with random value (although it is not required as this is done automatically in PHP).
As the seed value is random, it produces different results in each execution.
<?php //seed with microseconds function make_seed() { list($usec, $sec) = explode(' ', microtime()); return $sec + $usec * 1000000; } srand(make_seed()); //generate 10 pseudo-random value //between 0 and getrandmax() for ($i = 1; $i <= 10; $i++) { echo rand()."\n"; } ?>
The output of the above code will be:
1489097103 52646159 417163374 1140338404 932967394 1793355896 158034244 1981207412 2115064440 2013356126
Example:
Consider one more example where seed value is fixed. This facilitates the ability to reproduce the same result in each execution.
<?php //seed with fixed value srand(10); //generate 10 pseudo-random value //between 0 and getrandmax() for ($i = 1; $i <= 10; $i++) { echo rand()."\n"; } ?>
The output of the above code will be:
1656398468 641584702 44564466 1062123783 1360749216 951367352 1608044093 1786516046 1070535660 1252673902
❮ PHP Math Reference