(PHP 4, PHP 5, PHP 7)
mt_rand — Generate a better random value
$min
, int $max
)Many random number generators of older libcs have dubious or unknown characteristics and are slow. By default, PHP uses the libc random number generator with the rand() function. The mt_rand() function is a drop-in replacement for this. 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).
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.
minOptional lowest value to be returned (default: 0)
maxOptional highest value to be returned (default: mt_getrandmax())
A random integer value between min (or 0)
and max (or mt_getrandmax(), inclusive),
or FALSE if max is less than min.
| Version | Description |
|---|---|
| 5.3.4 |
Issues an E_WARNING and returns FALSE if
max < min.
|
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
The distribution of mt_rand() return values is biased
towards even numbers on 64-bit builds of PHP when
max is beyond 2^32.
This is because if max is greater than
the value returned by mt_getrandmax(), the output of the
random number generator must be scaled up.