php公用函数：生成随机数字大小写字母的N位随机字符串

//获取随机字符串
function get_randNum($len = 12)
{
  $chars = '0123456789abcdefghijklmnopqrstuvwABCDEFGHIGKLMNOPQRSTUVWXYZ';
  $str   = '';
  for ($i = 0; $i < $len; $i++) {
    $str .= $chars[mt_rand(0, strlen($chars) - 1)];
  }
  return $str;
}

Done！