C#代碼中如何比較兩個日期的大小？

C#中比較兩個日期大小的方法

       /// <summary>
        /// 比較兩個日期大小
        /// </summary>
        /// <param name="dateStr1">日期1</param>
        /// <param name="dateStr2">日期2</param>
        /// <param name="msg">返回信息</param>
        public void CompanyDate(string dateStr1, string dateStr2,ref string msg) {
            //將日期字符串轉換為日期對象
            DateTime t1 = Convert.ToDateTime(dateStr1);
            DateTime t2 = Convert.ToDateTime(dateStr2);
            //通過DateTIme.Compare()進行比較（）
            int compNum = DateTime.Compare(t1, t2);

            //t1> t2
            if (compNum > 0) {
                msg = "t1:(" + dateStr1 + ")大於" + "t2(" + dateStr2 + ")";              
            }
            //t1= t2
            if (compNum == 0) {
                msg = "t1:(" + dateStr1 + ")等於" + "t2(" + dateStr2 + ")";
            }
            //t1< t2
            if (compNum < 0) {
                msg = "t1:(" + dateStr1 + ")小於" + "t2(" + dateStr2 + ")";
            }
        }

調用的代碼

        public ActionResult Index()
        {
            //t1< t2
            string msg1 = string.Empty;
            string date1 = "2018-07-25";
            string date2 = "2018-07-27";
            CompanyDate(date1,date2,ref msg1);
            
            //t1> t2
            string msg2 = string.Empty;
            string date3 = "2018-07-27";
            string date4 = "2018-07-25";
            CompanyDate(date3, date4, ref msg2);

            return View();
        }

整體demo源碼

 public class TestController : Controller
    {
        // GET: Test
        public ActionResult Index()
        {
            //t1< t2
            string msg1 = string.Empty;
            string date1 = "2018-07-25";
            string date2 = "2018-07-27";
            CompanyDate(date1,date2,ref msg1);
            
            //t1> t2
            string msg2 = string.Empty;
            string date3 = "2018-07-27";
            string date4 = "2018-07-25";
            CompanyDate(date3, date4, ref msg2);

            return View();
        }

        /// <summary>
        /// 比較兩個日期大小
        /// </summary>
        /// <param name="dateStr1">日期1</param>
        /// <param name="dateStr2">日期2</param>
        /// <param name="msg">返回信息</param>
        public void CompanyDate(string dateStr1, string dateStr2,ref string msg) {
            //將日期字符串轉換為日期對象
            DateTime t1 = Convert.ToDateTime(dateStr1);
            DateTime t2 = Convert.ToDateTime(dateStr2);
            //通過DateTIme.Compare()進行比較（）
            int compNum = DateTime.Compare(t1, t2);

            //t1> t2
            if (compNum > 0) {
                msg = "t1:(" + dateStr1 + ")大於" + "t2(" + dateStr2 + ")";              
            }
            //t1= t2
            if (compNum == 0) {
                msg = "t1:(" + dateStr1 + ")等於" + "t2(" + dateStr2 + ")";
            }
            //t1< t2
            if (compNum < 0) {
                msg = "t1:(" + dateStr1 + ")小於" + "t2(" + dateStr2 + ")";
            }
        }
    }

具體效果圖：

1）圖1

2）圖2