日期验证控件

private void txtDateEmployed_TextChanged(object sender, EventArgs e)
{
            this.txtDateEmployed.BackColor = Color.White;
            //当控件失去焦点时
          this.txtDateEmployed.LostFocus += new EventHandler(txtInput_LostFocus);
}

void txtInput_LostFocus(object sender, EventArgs e)
{
            string time = this.txtDateEmployed.Text.Trim();

            //如果为空
          if (time == "")
            {
                //显示当前日期
             string now = DateTime.Now.ToLocalTime().ToString("yyyy/MM/dd");
                now = now.Replace("-", "/");
                this.txtDateEmployed.Text = now;
                return;
            }

            //只有分隔符
          if (time.Replace("/", "") == "")
            {
                this.txtDateEmployed.Text = "";
                return;
            }

            //超出日期范围
          if (int.Parse(time.Replace("/", "")) < 17530101 || int.Parse(time.Replace("/", "")) > 99991231)
            {
                this.txtDateEmployed.Focus();
                this.txtDateEmployed.SelectAll();
                this.txtDateEmployed.BackColor = Color.Yellow;
                return;
            }

            //检查日期是否合法
          if (!CheckDate(time.Replace("/", "")))
            {
                this.txtDateEmployed.Focus();
                this.txtDateEmployed.SelectAll();
                this.txtDateEmployed.BackColor = Color.Yellow;
                return;
            }

            time = time.Replace("/", "");
            //格式化时间
            time = time.Insert(4, "/");
            time = time.Insert(7, "/");
            this.txtDateEmployed.Text = time;
            this.txtDateEmployed.BackColor = Color.White;
}

/// <summary>
/// 验证日期合法性
/// </summary>
/// <param name="date">日期参数</param>
/// <returns>是否合法</returns>
private bool CheckDate(string date)
{
            try
            {
                //取出年月日
             int year = int.Parse(date.Substring(0, 4));
                int month = int.Parse(date.Substring(4, 2));
                int day = int.Parse(date.Substring(6, 2));
                int[] days = new int[] { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
                if (IsLeapYear(year))
                {
                    //如果是闰年
                days[1] = 29;
                }
                return year > 0 && month <= 12 && month > 0 && day <= days[month - 1] && day > 0;
            }
            catch
            {
                return false;
            }
}

/// <summary>
/// 判断是否是闰年
/// </summary>
/// <param name="year">年份</param>
/// <returns>是否是闰年</returns>
private bool IsLeapYear(int year)
{
            return (year % 4 == 0 || year % 400 == 0) && (year % 100 != 0); 
}