生成随机字符串 php

 /**
     +----------------------------------------------------------
     * 生成随机字符串
     +----------------------------------------------------------
     * @param int       $length  要生成的随机字符串长度
     * @param string    $type    随机码类型：0，数字+大小写字母；1，数字；2，小写字母；3，大写字母；4，特殊字符；-1，数字+大小写字母+特殊字符
     +----------------------------------------------------------
     * @return string
     +----------------------------------------------------------
     echo randCode(6,1);
 */
 function randCode($length = 32, $type = 0) {
     $arr = array(1 => "0123456789", 2 => "abcdefghijklmnopqrstuvwxyz", 3 => "ABCDEFGHIJKLMNOPQRSTUVWXYZ", 4 => "~@#$%^&*(){}[]|");
     if ($type == 0) {
         array_pop($arr);
         $string = implode("", $arr);
     } elseif ($type == "-1") {
         $string = implode("", $arr);
     } else {
         $string = $arr[$type];
     }
     $count = strlen($string) - 1;
     $code = '';
     for ($i = 0; $i < $length; $i++) {
         $code .= $string[rand(0, $count)];
     }
     return $code;
 }