PHP
数学 | Mathematics

srand

srand

(PHP 4, PHP 5, PHP 7)

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: 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 integer seed value.

Return Values

No value is returned.

Changelog

VersionDescription
7.1.0srand() 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

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https://secure.php.net/manual/en/function.srand.php