用这个可以来验证用户和生成随机密码--teaman
//----------------------------------------------------
        // function getsid()
        //
        // parameters : $nsize number of caracters, default 24
        // return value : 24 caracters string
        //
        // description : this function returns a random string
        // of 24 caracters that can be used to identify users
        // on your web site in a more secure way. you can also  
        // use this function to generate passwords.
        //----------------------------------------------------
        function getsid ($nsize=24) {
// randomize
            mt_srand ((double) microtime() * 1000000);
            for ($i=1; $i                 
                // if you wish to add numbers in your string,  
                // uncomment the two lines that are commented
                // in the if statement
                $nrandom = mt_rand(1,30);
                if ($nrandom                     // uppercase letters
                    $sessionid .= chr(mt_rand(65,90));
            //    } elseif ($nrandom             //        $sessionid .= mt_rand(0,9);
                } else {
                    // lowercase letters
                    $sessionid .= chr(mt_rand(97,122));
                }
}         
            return $sessionid;
        }
        // test the function  
        echo getsid(16);
    ?> 
以上就介绍了php生成sessionid和随机密码的例子，包括了方面的内容，希望对php教程有兴趣的朋友有所帮助。