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random_int

(PHP 7, PHP 8)

random_int获取生成加密安全、均匀分布的整数

说明

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

生成在指定最小值和最大值之间均匀分布的整数。

该函数生成的随机性适用于所有应用,包括生成长期秘密,如加密密钥。

此函数使用的随机性来源先后顺序如下:

  • Linux:» getrandom()/dev/urandom

  • FreeBSD >= 12(PHP >= 7.3):» getrandom()/dev/urandom

  • Windows(PHP >= 7.2):» CNG-API

    Windows:» CryptGenRandom

  • macOS(PHP >= 8.2;>= 8.1.9;>= 8.0.22 如果 CCRandomGenerateBytes 在编译时可用):CCRandomGenerateBytes()

    macOS(PHP >= 8.1;>= 8.0.2):arc4random_buf()、/dev/urandom

  • NetBSD >= 7(PHP >= 7.1;>= 7.0.1):arc4random_buf()、/dev/urandom

  • OpenBSD >= 5.5(PHP >= 7.1;>= 7.0.1):arc4random_buf()、/dev/urandom

  • DragonflyBSD(PHP >= 8.1):» getrandom()/dev/urandom

  • Solaris(PHP >= 8.1):» getrandom()/dev/urandom

  • 未提及的 PHP 版本和操作系统的组合:/dev/urandom
  • 如果没有可用的来源或它们都无法生成随机性,则将抛出 Random\RandomException

注意: 虽然此函数是 PHP 7.0 添加到 PHP 中,但是从 PHP 5.2 到 PHP 5.6 都可以用 » 用户级实现

参数

min

要返回的最小值。

max

要返回的最大值。

返回值

从闭合区间 [min, max] 返回加密安全、均匀分布的整数。minmax 都有可能返回。

错误/异常

更新日志

版本 说明
8.2.0 CSPRNG 失败时,此函数现在将抛出 Random\RandomException。之前抛出普通的 Exception

示例

示例 #1 random_int() 示例

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

以上示例的输出类似于:

int(248)
int(-898)

参见

add a note

User Contributed Notes 4 notes

up
15
s rotondo90 at gmail com
7 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);
?>
up
4
bens at effortlessis dot com
3 years 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.
up
0
ccb_bc at hotmail dot com
5 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());
?>
up
-1
Hayley Watson
10 months ago
A small function for generating version 4 GUIDs.

<?php
function v4uuid()
{
$a = str_pad(dechex(random_int(0x0000_0000, 0xffff_ffff)), '0', STR_PAD_LEFT);
$b = str_pad(dechex(random_int(0x0000, 0xffff)), '0', STR_PAD_LEFT);
$c = dechex(random_int(0x4000, 0x4fff));
$d = dechex(random_int(0x8000, 0xbfff));
$e = str_pad(dechex(random_int(0x0000_0000_0000, 0xffff_ffff_ffff)), '0', STR_PAD_LEFT);
return
"$a-$b-$c-$d-$e";
}
?>
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