Question

我在VB.net中有1个字符串

Dim str As String = "2014/08/15 19:45"

我有2次

Dim startDate As String = "6:30"
Dim endDate As String = "22:00"

如何比较“str”和“startDate”＆amp; “endDate”？

Answer 1

首先，您有字符串而不是DateTimes或TimeSpan。但如果你想比较它们，你需要两者。因此，请使用Date.Parse，Date.ParseExact（或...TryParse版本来检查无效数据）：

Dim str As String = "2014/08/15 19:45"
Dim dt1 = Date.ParseExact(str, "yyyy/MM/dd HH:mm", CultureInfo.InvariantCulture)

Dim startDate As String = "6:30"
Dim tsStart = TimeSpan.Parse(startDate)

Dim endDate As String = "22:00"
Dim tsEnd = TimeSpan.Parse(endDate)

现在你可以比较它们了：

If dt1.TimeOfDay >= tsStart AndAlso dt1.TimeOfDay <= tsEnd Then
 ' Yes, 19:45 is between  6:30 and 22:00 '
End If

Answer 2

首先，您应该使用日期来存储值。然后检查时间组件就是一件简单的事情。请注意，下面的实现是包含的（即如果时间恰好是开始或结束时间，它将打印消息。

    Dim dateToCheck As Date = Date.Parse("2014/08/15 19:45")

    ' The date portion doesn't matter, so I'm just using 1/1/1970.
    Dim startTimeDate As Date = New Date(1970, 1, 1, 6, 30, 0)
    Dim endTimeDate As Date = New Date(1970, 1, 1, 22, 0, 0)

    Dim afterOrEqualToStartTime As Boolean = (dateToCheck.Hour >= startTimeDate.Hour) And (dateToCheck.Minute >= startTimeDate.Minute) And (dateToCheck.Second >= startTimeDate.Second)

    Dim beforeOrEqualToEndTime As Boolean = (dateToCheck.Hour <= endTimeDate.Hour) And (dateToCheck.Minute <= endTimeDate.Minute) And (dateToCheck.Second <= endTimeDate.Second)

    If (afterOrEqualToStartTime And beforeOrEqualToEndTime) Then
        MsgBox("Date is between the start and end times")
    End If

Answer 3

 Dim str As String = "2014/08/15 19:45"
 Dim time As DateTime = DateTime.Parse(str)

'here get the hour and minutes, and now you can compare with the others
 Dim tmpTime As DateTime = time.ToString("t")

Answer 4

使用日期变量比较时间很困难。

使用容差的数据差异是处理二进制时间的一种方法。

我使用字符串：

    Dim dt As Date = "2014/08/15 22:45"
    Dim s As String = dt.ToString("H:MM")
    If s > "06:30" And s <= "22:00" Then
        MsgBox("yes")
    Else
        MsgBox("no")
    End If

注意样本中06:30的前导0。

如何在vb.net中比较两次

4 个答案: