mt_rand

(PHP 4, PHP 5, PHP 7, PHP 8)

mt_randGenerate a random value via the Mersenne Twister Random Number Generator

Description

mt_rand(): int
mt_rand(int $min, int $max): int

Many random number generators of older libcs have dubious or unknown characteristics and are slow. The mt_rand() function is a drop-in replacement for the older rand(). It uses a random number generator with known characteristics using the » Mersenne Twister, which will produce random numbers four times faster than what the average libc rand() provides.

If called without the optional min, max arguments mt_rand() returns a pseudo-random value between 0 and mt_getrandmax(). If you want a random number between 5 and 15 (inclusive), for example, use mt_rand(5, 15).

Attention

Cette fonction ne génère pas de valeurs cryptographiquement sûres, et ne doit pas être utilisée à des fins cryptographiques, ou à des fins qui exigent que les valeurs renvoyées soient indéchiffrables.

Si de l'aléatoire cryptographiquement sûre est requis, le Random\Randomizer peut être utilisé avec le moteur Random\Engine\Secure. Pour des cas d'usage simple, les fonctions random_int() et random_bytes() fournissent une API pratique et sûre qui est qui est soutenu par le CSPRNG du système d'exploitation.

Liste de paramètres

min

Optional lowest value to be returned (default: 0)

max

Optional highest value to be returned (default: mt_getrandmax())

Valeurs de retour

A random integer value between min (or 0) and max (or mt_getrandmax(), inclusive), or false if max is less than min.

Historique

Version Description
7.2.0 mt_rand() has received a bug fix for a modulo bias bug. This means that sequences generated with a specific seed may differ from PHP 7.1 on 64-bit machines.
7.1.0 rand() has been made an alias of mt_rand().
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.

Exemples

Exemple #1 mt_rand() example

<?php
echo mt_rand() . "\n";
echo
mt_rand() . "\n";

echo
mt_rand(5, 15);
?>

Résultat de l'exemple ci-dessus est similaire à :

1604716014
1478613278
6

Notes

Avertissement

min max range must be within the range mt_getrandmax(). i.e. (max - min) <= mt_getrandmax() Otherwise, mt_rand() may return poorer random numbers than it should.

Voir aussi

  • mt_srand() - Seeds the Mersenne Twister Random Number Generator
  • mt_getrandmax() - Show largest possible random value
  • random_int() - Get a cryptographically secure, uniformly selected integer
  • random_bytes() - Get cryptographically secure random bytes
  • rand() - Generate a random integer

add a note

User Contributed Notes 3 notes

up
9
Pawe Krawczyk
9 years ago
To reiterate the message about *not* using mt_rand() for anything security related, here's a new tool that has been just posted that recovers the seed value given a single mt_rand() output:

http://www.openwall.com/php_mt_seed/README
up
1
greald at ghvernuft dot nl
21 days ago
To see some systematic deviations from a universal distribution run:

<?php
$alfabet
= str_split('ADHKLMNPSTUWX');
$countalfabet = count($alfabet)-1;
$code = array_fill_keys($alfabet, 0);
for (
$L=0; $L<80*$countalfabet; $L++)
{
 
$lettr = floor(mt_rand ( 0, $countalfabet ));
 
$code[$alfabet[$lettr]]++;
}

foreach(
$code as $L => $Freq)
{
  for(
$F=0; $F<$Freq; $F++)
  {
    echo
$L;
  }
  echo
"\n<br/>";
}
?>
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