这是我简单的一行解决方案，以生成一个使用友好的随机密码，排除字符看起来像“1”和“l”，“O”和“0”，等等…这里是5个字符，但你可以很容易地改变它:

$user_password = substr(str_shuffle('abcdefghjkmnpqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ23456789'),0,5);

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;
}

@tasmaniski:你的答案对我有用。我也有同样的问题，我想把它推荐给那些一直在寻找同样答案的人。以下是来自@tasmaniski的留言:

<?php 
    $random = substr(md5(mt_rand()), 0, 7);
    echo $random;
?>

这是一个youtube视频，向我们展示如何创建一个随机数

$t = array_merge(range('0', '9'), range('a', 'z'), range('A', 'Z'));
echo join('', array_map(function() use($t) { return $t[array_rand($t)]; }, range(1, 15)));

或一行程序

echo join('', array_map(function() { return substr('0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ', rand(0, 61), 1); }, range(1, 15)));

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);
}

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;
    }