1.产生随机字符串函数

function random($length) {
 $hash = '';
 $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz';
 $max = strlen($chars) - 1;
 mt_srand((double)microtime() * 1000000);
 for($i = 0; $i < $length; $i++) {
  $hash .= $chars[mt_rand(0, $max)];
 }
 return $hash;
}

2.截取一定长度的字符串

注：该函数对GB2312使用有效

function wordscut($string, $length ,$sss=0) {
 if(strlen($string) > $length) {
               if($sss){
                      $length=$length - 3;
                      $addstr=' ...';
                }
  for($i = 0; $i < $length; $i++) {
   if(ord($string[$i]) > 127) {
    $wordscut .= $string[$i].$string[$i + 1];
    $i++;
   } else {
    $wordscut .= $string[$i];
   }
  }
  return $wordscut.$addstr;

 }
 return $string;
}

3.取得客户端IP地址

function GetIP(){
             if (getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"), "unknown"))
                   $ip = getenv("HTTP_CLIENT_IP");
             else if (getenv("HTTP_X_FORWARDED_FOR") && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown"))
                   $ip = getenv("HTTP_X_FORWARDED_FOR");
             else if (getenv("REMOTE_ADDR") && strcasecmp(getenv("REMOTE_ADDR"), "unknown"))
                   $ip = getenv("REMOTE_ADDR");
             else if (isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], "unknown"))
                   $ip = $_SERVER['REMOTE_ADDR'];
             else
                  $ip = "unknown";
             return($ip);
}

4.创建相应的文件夹

function createdir($dir='')
{
        if (!is_dir($dir))
        {
            $temp = explode('/',$dir);
            $cur_dir = '';
            for($i=0;$i<count($temp);$i++)
            {
                $cur_dir .= $temp[$i].'/';
                if (!is_dir($cur_dir))
                {