# mt_rand

(PHP 4, PHP 5, PHP 7)

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

### Description

mt_rand ( void ) : 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.
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.

### See Also

- mt_srand() - Seeds the Mersenne Twister Random Number Generator
- mt_getrandmax() - Show largest possible random value
- random_int() - Generates cryptographically secure pseudo-random integers
- random_bytes() - Generates cryptographically secure pseudo-random bytes
- openssl_random_pseudo_bytes() - Generate a pseudo-random string of bytes
- rand() - Generate a random integer