PHP Manual: Generate a random value via the Mersenne Twister Random Number Generator

Description

int mt_rand ( void )

int mt_rand ( int $min , int $max )

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
7.1.0	rand has been made an alias of mt_rand.
7.1.0	mt_randhas 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 paramter.
5.3.4	Issues an `E_WARNING` and returns `FALSE` if `max` < `min`.

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.

mt_rand