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srand

(PHP 4, PHP 5, PHP 7)

srandSeed the random number generator

Description

srand ([ int $seed ] ) : 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.

Note: As of PHP 7.1.0, srand() has been made an alias of mt_srand().

Parameters

seed

An arbitrary int seed value.

Return Values

No value is returned.

Changelog

Version Description
7.1.0 srand() has been made an alias of mt_srand().

Examples

Example #1 srand() example

<?php
// seed with microseconds
function make_seed()
{
  list($usec, $sec) = explode(' ', microtime());
  return $sec + $usec * 1000000;
}
srand(make_seed());
$randval = rand();
?>

See Also

  • rand() - Generate a random integer
  • getrandmax() - Show largest possible random value
  • mt_srand() - Seeds the Mersenne Twister Random Number Generator

© 1997–2020 The PHP Documentation Group
Licensed under the Creative Commons Attribution License v3.0 or later.
https://www.php.net/manual/en/function.srand.php