Php/docs/function.mt-rand
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 |
Examples
Example #1 mt_rand() example
<?phpecho 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
