mt_rand

(PHP 4, PHP 5, PHP 7)

mt_rand — Generate a random value via the Mersenne Twister Random Number Generator

Description

mt_rand ( ) : int

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

Caution

This function does not generate cryptographically secure values, and should not be used for cryptographic purposes. If you need a cryptographically secure value, consider using random_int(), random_bytes(), or openssl_random_pseudo_bytes() instead.

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).

Parameters

min: Optional lowest value to be returned (default: 0)
max: Optional highest value to be returned (default: mt_getrandmax())

Return Values

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

Changelog

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.

Examples

Example #1 mt_rand() example

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

echo mt_rand(5, 15);
?>

The above example will output something similar to:

1604716014
1478613278
6

Notes

Warning

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.