通过身份证号码判断男女

/// <summary>
        /// 通过身份证号码判断男女
        /// </summary>
        /// <param name="strIDCard">空：不能为空。位数：位数不对。NULL:程序异常</param>
        public static string GetSexByIDCard(string strIDCard)
        {
            try
            {
                string strSex = "";
                //获取得到输入的身份证号码
                if (string.IsNullOrEmpty(strIDCard))
                {
                    //身份证号码不能为空，如果为空返回
                    strSex = "空";
                    return strSex;
                }
                else
                {
                    //身份证号码只能为15位或18位其它不合法
                    if (strIDCard.Length != 15 && strIDCard.Length != 18)
                    {
                        strSex = "位数";
                        return strSex;
                    }
                }

                //string birthday = "";
                string sex = "";

                //处理18位的身份证号码从号码中得到生日和性别代码
                if (strIDCard.Length == 18)
                {
                    //birthday = strIDCard.Substring(6, 4) + "-" + strIDCard.Substring(10, 2) + "-" + strIDCard.Substring(12, 2);
                    sex = strIDCard.Substring(14, 3);
                }
                //处理15位的身份证号码从号码中得到生日和性别代码
                if (strIDCard.Length == 15)
                {
                    //birthday = "19" + strIDCard.Substring(6, 2) + "-" + strIDCard.Substring(8, 2) + "-" + strIDCard.Substring(10, 2);
                    sex = strIDCard.Substring(12, 3);
                }
                //textBox_Birthday.Text = birthday;

                //性别代码为偶数是女性奇数为男性
                if (int.Parse(sex)%2 == 0)
                {
                    strSex = "女";
                }
                else
                {
                    strSex = "男";
                }
                return strSex;
            }
            catch
            {

                return null;
            }
        }