在 asp.net 中比较 StartDate 和 EndDate 时的混乱

发布于 2024-12-07 11:13:16 字数 271 浏览 0 评论 0原文

在我的 asp.net 应用程序中比较 StartDate 和 EndDate 时，我有点困惑。

EndDate:    10/1/2011
StartDate:  9/30/2011

下面的 if 语句根据上面的日期值返回 true。

如果 strEndDate < strStartDate 那么

我认为 If 语句应该返回 false。这个概念应该是，如果 EndDate 早于 StartDate，则显示错误消息。

原文

I am a bit confused when comparing StartDate and EndDate in my asp.net app.

EndDate:    10/1/2011
StartDate:  9/30/2011

The if statement below returns true, based on the date values above.

If strEndDate < strStartDate Then

I would think the If statement shoudl return false. The concept is supposed to be that if EndDate is earlier than StartDate, display an error message.

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清风疏影 2024-12-14 11:13:16

我假设由于您的变量名为 strEndDate 和 strStartDate，因此它们是字符串，而不是 DateTime。因为它们是字符串，并且因为 '1' < '9'（字符串中的第一个字符），strEndDate 确实“小于”strStartDate。

在比较之前将值转换为 DateTime：

If DateTime.Parse(strEndDate) < DateTime.Parse(strStartDate) Then
    '...
End If

I'm assuming that since your variables are called strEndDate and strStartDate that they're strings, not DateTimes. Since they're strings, and since '1' < '9' (the first characters in the strings), strEndDate is indeed "less than" strStartDate.

Convert the values to DateTime before comparing:

If DateTime.Parse(strEndDate) < DateTime.Parse(strStartDate) Then
    '...
End If

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星光不落少年眉 2024-12-14 11:13:16

如果这些是 DateTime 变量，则该代码的计算结果应为 true。如果不是，您应该将它们转换为 DateTime。

DateTime start = DateTime.Parse(strStartDate);
DateTime close = DateTime.Parse(strEndDate);

if (close > start)
    //do something

您还可以像这样比较它们：

if ((close - start).TotalDays > 0)
    //do something

正如 Rick Schott 指出的，您还可以使用 DateTime.Compare

If those are DateTime variables, that code should evaluate to true. If not, you should convert them to DateTime.

DateTime start = DateTime.Parse(strStartDate);
DateTime close = DateTime.Parse(strEndDate);

if (close > start)
    //do something

You can also compare them like this:

if ((close - start).TotalDays > 0)
    //do something

As Rick Schott pointed out, you can also use DateTime.Compare

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极度宠爱 2024-12-14 11:13:16

您应该使用 DateTime.Compare。

Dim date1 As Date = DateTime.Parse(strStartDate)
Dim date2 As Date = DateTime.Parse(strEndDate)
Dim result As Integer = DateTime.Compare(date1, date2)
Dim relationship As String

If result < 0 Then
   relationship = "is earlier than"
ElseIf result = 0 Then
   relationship = "is the same time as"         
Else
   relationship = "is later than"
End If

Console.WriteLine("{0} {1} {2}", date1, relationship, date2)
' The example displays the following output:
'    8/1/2009 12:00:00 AM is earlier than 8/1/2009 12:00:00 PM

You should be using DateTime.Compare.

Dim date1 As Date = DateTime.Parse(strStartDate)
Dim date2 As Date = DateTime.Parse(strEndDate)
Dim result As Integer = DateTime.Compare(date1, date2)
Dim relationship As String

If result < 0 Then
   relationship = "is earlier than"
ElseIf result = 0 Then
   relationship = "is the same time as"         
Else
   relationship = "is later than"
End If

Console.WriteLine("{0} {1} {2}", date1, relationship, date2)
' The example displays the following output:
'    8/1/2009 12:00:00 AM is earlier than 8/1/2009 12:00:00 PM

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