php生成不重复随机数

[php]
function crypto_rand_secure($min, $max) {
$range = $max – $min;
if ($range < 0) return $min; // not so random…
$log = log($range, 2);
$bytes = (int) ($log / 8) + 1; // length in bytes
$bits = (int) $log + 1; // length in bits
$filter = (int) (1 << $bits) – 1; // set all lower bits to 1
do {
$rnd = hexdec(bin2hex(openssl_random_pseudo_bytes($bytes)));
$rnd = $rnd & $filter; // discard irrelevant bits
} while ($rnd >= $range);
return $min + $rnd;
}

function getToken($length){
$token = "";
$codeAlphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
//$codeAlphabet.= "abcdefghijklmnopqrstuvwxyz";
$codeAlphabet.= "0123456789";
for($i=0;$i<$length;$i++){
$token .= $codeAlphabet[crypto_rand_secure(0,strlen($codeAlphabet))];
}
return $token;
}
[/php]

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