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

我说,把几个最好的答案放在一起- str_suffle和range对我来说是新的:

echo generateRandomString(25); // Example of calling it

function generateRandomString($length = 10) {
    return substr(str_shuffle(implode(array_merge(range(0,9), range('A', 'Z'), range('a', 'z')))), 0, $length);
}

其他回答

只使用PHP本地函数的参数化一行程序,从PHP 5.1.0开始工作

str_shuffle(implode('', (array_intersect_key(($map =  array_map('chr', array_merge(array_map('mt_rand', array_fill(0, $length = 25, 48), array_fill(0,$length,57)),array_map('mt_rand', array_fill(0, $length, 65), array_fill(0,$length,90)),array_map('mt_rand', array_fill(0, $length, 97), array_fill(0,$length,122))))), array_flip($keys = array_rand($map, $length))))))

具有上面讨论的一些函数的类。

$options['numeric'] = true;
$options['uppercase'] = true;
$options['lowercase'] = true;
$new = new RandomString($options);

class RandomString
{
    /**
     * @var array
     */
    private $default = ['numeric' => true, 'uppercase' => true, 'lowercase' => true];

    /**
     * @var array
     */
    private $options;

    /**
     * array
     */
    private $whitelist = ['numeric', 'uppercase', 'lowercase'];

    /**
     * RandomString constructor.
     *
     * @param array $options
     */
    public function __construct(array $options = [])
    {
        $this->options = $this->default;
        if(!empty($options))
        {
            $options = array_intersect_key($options, array_flip($this->whitelist));
            if(empty($options))
            {
                $this->options = $this->default;
            }else
            {
                $this->options = $options;
            }
        }
    }

    /**
     * @return string
     */
    private function returnCharacters(){

        $options = $this->options;

        $numbers = '0123456789';
        $uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
        $lowercase = "abcdefghijklmnopqrstuvwxyz";

        $characters = '';
        if(isset($options['numeric']) && $options['numeric'] === true){
            $characters .= $numbers;
        }

        if(isset($options['uppercase']) && $options['uppercase'] === true){
            $characters .= $uppercase;
        }

        if(isset($options['lowercase']) && $options['lowercase'] === true){
            $characters .= $lowercase;
        }
        return $characters;
    }

    /**
     * @param $length
     * @param $quantity
     * @return string
     */
    public function randomString($length, $quantity) {

        $string = '';
        $characters = $this->returnCharacters();

        for ($j = 0; $j < $quantity; $j++) {
            for($i = 0; $i < $length; $i++){
                $string .= $characters[mt_rand(0, strlen($characters) - 1)];
            }
            $string .= "\n";
        }
        return $string;
    }

    /**
     * @return array
     */
    public function getOptions()
    {
        return $this->options;
    }

    /**
     * @return mixed
     */
    public function getWhitelist()
    {
        return $this->whitelist;
    }

根据您的应用程序(我希望生成密码),您可以使用

$string = base64_encode(openssl_random_pseudo_bytes(30));

由于是base64,它们可以包含=或-以及所请求的字符。您可以生成一个更长的字符串,然后过滤和修剪它以删除它们。

Openssl_random_pseudo_bytes似乎是在php中生成适当随机数的推荐方法。为什么rand不用/dev/random,我不知道。

从php7开始,就有了random_bytes函数。 https://www.php.net/manual/ru/function.random-bytes.php 你可以生成一个这样的随机字符串

<?php
$bytes = random_bytes(5);
var_dump(bin2hex($bytes));
?>

试试这个,它可以生成到master的长度。但它简单,适合小字符串。

$master="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
$master_array = str_split($master);
shuffle($master_array);
print_r(implode("",array_slice($master_array,0,10)));