Rechercher une fonction PHP

mt_srand

(PHP 4, PHP 5, PHP 7)

mt_srandSeeds the Mersenne Twister Random Number Generator

Description

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.

PHP: mt_srand - Manual Home of Manuel PHP  Contents Haut

Parameters

seed

An arbitrary integer 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.

PHP: mt_srand - Manual Home of Manuel PHP  Contents Haut

Return Values

No value is returned.

PHP: mt_srand - Manual Home of Manuel PHP  Contents Haut

Changelog

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.
5.2.1 The Mersenne Twister implementation in PHP now uses a new seeding algorithm by Richard Wagner. Identical seeds no longer produce the same sequence of values they did in previous versions. This behavior is not expected to change again, but it is considered unsafe to rely upon it nonetheless.

PHP: mt_srand - Manual Home of Manuel PHP  Contents Haut

Examples

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();
?>

PHP: mt_srand - Manual Home of Manuel PHP  Contents Haut

See Also

  • mt_rand() - Generate a random value via the Mersenne Twister Random Number Generator
  • mt_getrandmax() - Show largest possible random value
  • srand() - Seed the random number generator

Find a PHP function

English translation

You have asked to visit this site in English. For now, only the interface is translated, but not all the content yet.

If you want to help me in translations, your contribution is welcome. All you need to do is register on the site, and send me a message asking me to add you to the group of translators, which will give you the opportunity to translate the pages you want. A link at the bottom of each translated page indicates that you are the translator, and has a link to your profile.

Thank you in advance.

Document created the 30/01/2003, last modified the 26/10/2018
Source of the printed document:https://www.gaudry.be/en/php-rf-function.mt-srand.html

The infobrol is a personal site whose content is my sole responsibility. The text is available under CreativeCommons license (BY-NC-SA). More info on the terms of use and the author.

References

  1. View the html document Language of the document:fr Manuel PHP : http://php.net

These references and links indicate documents consulted during the writing of this page, or which may provide additional information, but the authors of these sources can not be held responsible for the content of this page.
The author This site is solely responsible for the way in which the various concepts, and the freedoms that are taken with the reference works, are presented here. Remember that you must cross multiple source information to reduce the risk of errors.

Contents Haut