Submit a Pull Request Report a Bug

    random_int

    (PHP 7, PHP 8)

    random_int — Get a cryptographically secure, uniformly selected integer

    Descrição

    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.

    As fontes de aleatoriedade dessa função são:

    Nota: Embora essa função tenha sido adicionado no PHP 7.0, existe » implementação userland disponível para PHP 5.2 ao 5.6.

    Parâmetros

    min

    The lowest value to be returned.

    max

    The highest value to be returned.

    Valor Retornado

    A cryptographically secure, uniformly selected integer from the closed interval [min, max]. Both min and max are possible return values.

    Erros

    • Se uma fonte de aleatoriedade não for encontrada uma Random\RandomException será lançada.
    • No caso de parâmetros inválidos um TypeError será lançado.
    • If max is less than min, an ValueError will be thrown.

    Changelog

    Versão Descrição
    8.2.0 In case of a CSPRNG failure, this function will now throw a Random\RandomException. Previously a plain Exception was thrown.

    Exemplos

    Exemplo #1 random_int() example

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

    O exemplo acima produzirá algo semelhante a:

    int(248)
int(-898)

    Veja Também

    ＋add a note

    User Contributed Notes 3 notes

    up
    14
    s rotondo90 at gmail com
    6 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
    7
    ccb_bc at hotmail dot com
    3 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
    3
    bens at effortlessis dot com
    2 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.
    ＋add a note
    To Top