[TOC] #### 1. 生成指定长度的随机英文数字字符串 --- ```php /** * 生成指定长度的随机英文数字字符串 * @param int $length 字符串长度 * @return string 成的随机字符串 */ function generateRandomString($length) { $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'; $randomString = ''; for ($i = 0; $i < $length; $i++) { $randomString .= $characters[rand(0, strlen($characters) - 1)]; } return $randomString; } ```