营地日期时间问题 [英] Problem in campareing datetime

问题描述

我在我的代码中面临一个问题，我将今天的日期与数据库中的日期进行比较，这是我的代码。这里label10.Text包含数据库中的日期。基本上我正在制作一个提醒应用程序。如果数据库日期与今天的日期匹配，则应发送提醒电子邮件

 DateTime dt = DateTime.Parse（label10.Text）; 
 long t = dt.ToFileTime（）; 
 DateTime date1 = DateTime.Today; 
 DateTime date2 = new DateTime（t）; 
 // DateTime date2 = new DateTime（Convert.ToInt64（label10.Text））; 
 // DateTime date2 = new DateTime（2015,9,16）; 
 int result = DateTime.Compare（date1，date2）; 
字符串关系; 
 if（结果> 0）
 {
 relationship =早于; 
 // SendEmail（）; 
} 
 else if（result == 0）
 {
 relationship =与...同时; 
 SendEmail（）; 
 //MessageBox.Show（相同）; 
} 
 
其他
 {
 relationship =晚于; 
 SendEmail（）; 
 //MessageBox.Show（以后是）; 
} 
 Console.WriteLine（{0} {1} {2}，date1，relationship，date2）; 

现在问题是当我运行应用程序时，date2被填充29.09.15而标签10显示为30.09.15。我不明白为什么会发生这种情况

解决方案

确定 - 永远不要将DateTime值与绝对相等进行比较：它们是精确到刻度 [ ^ ]，这是百万分之一的一秒钟。



这意味着在实践中，你的代码很可能恰好匹配相等。



相反，请考虑检查差异：

 Timespan diff = date1  -  date2; 
  if （diff.TotalSeconds <   0 ）
 ... 
  else   if （diff.TotalSeconds ==  0 ）
 ... 
  else  
 .. 。

这至少会给你一个与其匹配的一秒钟窗口（或者如果你的计时器不准确，则使用TotalMinutes）

hii i am facing a problem in my code in which i am comparing today's date with the date in database this is my code. Here label10.Text is containing the date from database. Basically i am making a reminder app. If the database date matches with todays date then it should send a reminder email

DateTime dt = DateTime.Parse(label10.Text);
            long t = dt.ToFileTime();
            DateTime date1 = DateTime.Today;
            DateTime date2 = new DateTime(t);
            //DateTime date2 = new DateTime(Convert.ToInt64(label10.Text));
            //DateTime date2 = new DateTime(2015,9,16);
            int result = DateTime.Compare(date1, date2);
            string relationship;
            if (result > 0)
            {
                relationship = "is earlier than";
                //SendEmail();               
            }
            else if (result == 0)
            {
                relationship = "is the same time as";
                SendEmail();
                //MessageBox.Show("is same");
            }
            
            else
            {
                relationship = "is later than";
                SendEmail();
                //MessageBox.Show("is later");
            }
            Console.WriteLine("{0} {1} {2}", date1, relationship, date2);

Now the problem is when i run the application the date2 gets filled with 29.09.15 whereas label 10 shows 30.09.15. i am not getting why it is happening

解决方案

OK - never compare DateTime values for absolute equality: they are accurate to a tick[^], which is one ten millionth of a second.

That means that in practice there is very, very little chance that your code will ever match equality precisely.

So instead, consider checking the difference:

Timespan diff = date1 - date2;
if (diff.TotalSeconds < 0)
   ...
else if (diff.TotalSeconds == 0)
   ...
else 
   ...

That at least gives you a one-second window in which it will match (or if your timer is not that accurate, use TotalMinutes instead)

这篇关于营地日期时间问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！