C# 根据身份证号码判断出生日期和性别

                //获取得到输入的身份证号码
                string identityCard = textBox_IdentityCard.Text.Trim();

                if (string.IsNullOrEmpty(identityCard))
                {
                    //身份证号码不能为空，如果为空返回
                    MessageBox.Show("身份证号码不能为空！");
                    if (textBox_IdentityCard.CanFocus)
                    {
                        textBox_IdentityCard.Focus();//设置当前输入焦点为textBox_IdentityCard
                    }
                    return;
                }
                else
                {
                    //身份证号码只能为15位或18位其它不合法
                    if (identityCard.Length != 15 && identityCard.Length != 18)
                    {
                        MessageBox.Show("身份证号码为15位或18位，请检查！");
                        if (textBox_IdentityCard.CanFocus)
                        {
                            textBox_IdentityCard.Focus();
                        }
                        return;
                    }
                }

                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 (identityCard.Length == 18)
                {
                    birthday = identityCard.Substring(6, 4) + "-" + identityCard.Substring(10, 2) + "-" + identityCard.Substring(12, 2);
                    sex = identityCard.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 (identityCard.Length == 15)
                {
                    birthday = "19" + identityCard.Substring(6, 2) + "-" + identityCard.Substring(8, 2) + "-" + identityCard.Substring(10, 2);
                    sex = identityCard.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)
                {
                    this.comboBox_Sex.Text = "女";
                }
                else
                {
                    this.comboBox_Sex.Text = "男";
                }