我试图在PHP中创建一个随机字符串，我得到绝对没有输出:
<?php
function RandomString()
{
$characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
$randstring = '';
for ($i = 0; $i < 10; $i++) {
$randstring = $characters[rand(0, strlen($characters))];
}
return $randstring;
}
RandomString();
echo $randstring;
我做错了什么?
当前回答
这是另一个解决方案。
function genRandomString($length = 10)
{
if($length < 1)
$length = 1;
return substr(preg_replace("/[^A-Za-z0-9]/", '', base64_encode(openssl_random_pseudo_bytes($length * 2))), 0, $length);
}
PS.我在Ubuntu上使用PHP 7.2。
其他回答
Laravel 5框架中的辅助函数
/**
* Generate a "random" alpha-numeric string.
*
* Should not be considered sufficient for cryptography, etc.
*
* @param int $length
* @return string
*/
function str_random($length = 16)
{
$pool = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
return substr(str_shuffle(str_repeat($pool, $length)), 0, $length);
}
一个班轮。
对于具有唯一性的大字符串，它是快速的。
function random_string($length){
return substr(str_repeat(md5(rand()), ceil($length/32)), 0, $length);
}
function rndStr($len = 64) {
$randomData = file_get_contents('/dev/urandom', false, null, 0, $len) . uniqid(mt_rand(), true);
$str = substr(str_replace(array('/','=','+'),'', base64_encode($randomData)),0,$len);
return $str;
}
以前的答案会生成不安全或难以输入的密码。
这是安全的，并且提供了用户更有可能实际使用的密码，而不是因为一些薄弱的东西而被丢弃。
// NOTE: On PHP 5.x you will need to install https://github.com/paragonie/random_compat
/**
* Generate a password that can easily be typed by users.
*
* By default, this will sacrifice strength by skipping characters that can cause
* confusion. Set $allowAmbiguous to allow these characters.
*/
static public function generatePassword($length=12, $mixedCase=true, $numericCount=2, $symbolCount=1, $allowAmbiguous=false, $allowRepeatingCharacters=false)
{
// sanity check to prevent endless loop
if ($numericCount + $symbolCount > $length) {
throw new \Exception('generatePassword(): $numericCount + $symbolCount are too high');
}
// generate a basic password with just alphabetic characters
$chars = 'qwertyupasdfghjkzxcvbnm';
if ($mixedCase) {
$chars .= 'QWERTYUPASDFGHJKZXCVBNML';
}
if ($allowAmbiguous) {
$chars .= 'iol';
if ($mixedCase) {
$chars .= 'IO';
}
}
$password = '';
foreach (range(1, $length) as $index) {
$char = $chars[random_int(0, strlen($chars) - 1)];
if (!$allowRepeatingCharacters) {
while ($char == substr($password, -1)) {
$char = $chars[random_int(0, strlen($chars) - 1)];
}
}
$password .= $char;
}
// add numeric characters
$takenSubstitutionIndexes = [];
if ($numericCount > 0) {
$chars = '23456789';
if ($allowAmbiguous) {
$chars .= '10';
}
foreach (range(1, $numericCount) as $_) {
$index = random_int(0, strlen($password) - 1);
while (in_array($index, $takenSubstitutionIndexes)) {
$index = random_int(0, strlen($password) - 1);
}
$char = $chars[random_int(0, strlen($chars) - 1)];
if (!$allowRepeatingCharacters) {
while (substr($password, $index - 1, 1) == $char || substr($password, $index + 1, 1) == $char) {
$char = $chars[random_int(0, strlen($chars) - 1)];
}
}
$password[$index] = $char;
$takenSubstitutionIndexes[] = $index;
}
}
// add symbols
$chars = '!@#$%&*=+?';
if ($allowAmbiguous) {
$chars .= '^~-_()[{]};:|\\/,.\'"`<>';
}
if ($symbolCount > 0) {
foreach (range(1, $symbolCount) as $_) {
$index = random_int(0, strlen($password) - 1);
while (in_array($index, $takenSubstitutionIndexes)) {
$index = random_int(0, strlen($password) - 1);
}
$char = $chars[random_int(0, strlen($chars) - 1)];
if (!$allowRepeatingCharacters) {
while (substr($password, $index - 1, 1) == $char || substr($password, $index + 1, 1) == $char) {
$char = $chars[random_int(0, strlen($chars) - 1)];
}
}
$password[$index] = $char;
$takenSubstitutionIndexes[] = $index;
}
}
return $password;
}
试试这个:
function generate_name ($length = LENGTH_IMG_PATH) {
$image_name = "";
$possible = "0123456789abcdefghijklmnopqrstuvwxyz";
$i = 0;
while ($i < $length) {
$char = substr($possible, mt_rand(0, strlen($possible)-1), 1);
if (!strstr($image_name, $char)) {
$image_name .= $char;
$i++;
}
}
return $image_name;
}
