random_int

Here is a simple backporting function, it works for PHP >= 5.1<?phpif (!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);?>

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.

A small function for generating version 4 GUIDs.<?phpfunction 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";}?>

<?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());?>