PHP - Manual: random_int

2024-11-13

random_int

(PHP 7, PHP 8)

random_int — Generates cryptographically secure pseudo-random integers

说明

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

Generates cryptographic random integers that are suitable for use where unbiased results are critical, such as when shuffling a deck of cards for a poker game.

The sources of randomness used for this function are as follows:

On Windows, » CryptGenRandom() will always be used. As of PHP 7.2.0, the » CNG-API will always be used instead.
On Linux, the » getrandom(2) syscall will be used if available.
On other platforms, /dev/urandom will be used.
If none of the aforementioned sources are available, then an Exception will be thrown.

注意: Although this function was added to PHP in PHP 7.0, a » userland implementation is available for PHP 5.2 to 5.6, inclusive.

参数

min: The lowest value to be returned, which must be PHP_INT_MIN or higher.
max: The highest value to be returned, which must be less than or equal to PHP_INT_MAX.

返回值

Returns a cryptographically secure random integer in the range min to max, inclusive.

错误／异常

If an appropriate source of randomness cannot be found, an Exception will be thrown.
If invalid parameters are given, a TypeError will be thrown.
If max is less than min, an Error will be thrown.

范例

示例 #1 random_int() example


<?php
var_dump(random_int(100, 999));
var_dump(random_int(-1000, 0));
?>

以上例程的输出类似于：

int(248)
int(-898)

参见

random_bytes() - Generates cryptographically secure pseudo-random bytes

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User Contributed Notes 4 notes

down

s rotondo90 at gmail com ¶

5 years ago


Here is a simple backporting function, it works for PHP >= 5.1

<?php
if (!function_exists('random_int')) {
    function random_int($min, $max) {
        if (!function_exists('mcrypt_create_iv')) {
            trigger_error(
                'mcrypt must be loaded for random_int to work', 
                E_USER_WARNING
            );
            return null;
        }
        
        if (!is_int($min) || !is_int($max)) {
            trigger_error('$min and $max must be integer values', E_USER_NOTICE);
            $min = (int)$min;
            $max = (int)$max;
        }
        
        if ($min > $max) {
            trigger_error('$max can\'t be lesser than $min', E_USER_WARNING);
            return null;
        }
        
        $range = $counter = $max - $min;
        $bits = 1;
        
        while ($counter >>= 1) {
            ++$bits;
        }
        
        $bytes = (int)max(ceil($bits/8), 1);
        $bitmask = pow(2, $bits) - 1;

        if ($bitmask >= PHP_INT_MAX) {
            $bitmask = PHP_INT_MAX;
        }

        do {
            $result = hexdec(
                bin2hex(
                    mcrypt_create_iv($bytes, MCRYPT_DEV_URANDOM)
                )
            ) & $bitmask;
        } while ($result > $range);

        return $result + $min;
    }
}
?>

Randomness test

<?php
$max = 100; // number of random values
$test = 1000000;

$array = array_fill(0, $max, 0);

for ($i = 0; $i < $test; ++$i) {
    ++$array[random_int(0, $max-1)];
}

function arrayFormatResult(&$item) {
    global $test, $max; // try to avoid this nowdays ;)
    
    $perc = ($item/($test/$max))-1;
    $item .= ' '. number_format($perc, 4, '.', '') .'%';
}

array_walk($array, 'arrayFormatResult');

print_r($array);
?>

down

ccb_bc at hotmail dot com ¶

2 years ago


<?php 
    // PHP >= 7
    function str_rand(int $length = 16){
        $x = '';
        for($i = 1; $i <= $length; $i++){
            $x .= dechex(random_int(0,255));
        }
        return substr($x, 0, $length);
    }
    var_dump(str_rand());
?>

down

bens at effortlessis dot com ¶

1 year ago


On my system (5th gen i7) random_int() takes about 14x longer to do the same number of calculations than rand(). 

for ($i=0; $i<10000000; $i++)
        $x = rand(1, PHP_INT_MAX);

Takes 0.86 seconds for rand(), 12.29 seconds for random_int(). So use random_int() somewhat sparingly. 

If it's not really important to be truly random, use rand() instead, especially in a tight loop.

down

-40

info at raymondrodgers dot com ¶

6 years ago


This function is based on Andrew Moore's UUID generation function on the uniqid function; it has been updated to use random_int() on PHP 7.0 or later yet continue to function with earlier versions using mt_rand().

function generateUUIDv4()
{
    if(version_compare(PHP_VERSION,'7.0.0', '<') )
    {
        return sprintf('%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
        
        // 32 bits for "time_low"
        mt_rand(0, 0xffff), mt_rand(0, 0xffff),
        
        // 16 bits for "time_mid"
        mt_rand(0, 0xffff),
        
        // 16 bits for "time_hi_and_version",
        // four most significant bits holds version number 4
        mt_rand(0, 0x0fff) | 0x4000,
        
        // 16 bits, 8 bits for "clk_seq_hi_res",
        // 8 bits for "clk_seq_low",
        // two most significant bits holds zero and one for variant DCE1.1
        mt_rand(0, 0x3fff) | 0x8000,
        
        // 48 bits for "node"
        mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff)
        );
    }
    else
    {
        return sprintf('%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
        
        // 32 bits for "time_low"
        random_int(0, 0xffff), random_int(0, 0xffff),
        
        // 16 bits for "time_mid"
        random_int(0, 0xffff),
        
        // 16 bits for "time_hi_and_version",
        // four most significant bits holds version number 4
        random_int(0, 0x0fff) | 0x4000,
        
        // 16 bits, 8 bits for "clk_seq_hi_res",
        // 8 bits for "clk_seq_low",
        // two most significant bits holds zero and one for variant DCE1.1
        random_int(0, 0x3fff) | 0x8000,
        
        // 48 bits for "node"
        random_int(0, 0xffff), random_int(0, 0xffff), random_int(0, 0xffff)
        );
    }
}

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官方地址：https://www.php.net/manual/en/function.random-int.php

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random_int

说明

参数

返回值

错误／异常

范例

参见

User Contributed Notes 4 notes