Math Functions
PHP Manual

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: As of PHP 4.2.0, there is no need to seed the random number generator with srand or mt_srand as this is now done automatically.

Parameters

seed

Optional seed value

Return Values

No value is returned.

Changelog

Version Description
4.2.0 The seed becomes optional and defaults to a random value if omitted.

Examples

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();
?>

See Also

  • rand
  • getrandmax
  • mt_srand