Question

目前，我有这段代码。

Dim iCurrentDate As Date = Now
Dim iStartDate As Date = CDate(dtFrom.Text)
Dim iEndDate As Date = CDate(dtTo.Text)

If (iCurrentDate > iStartDate) And (iCurrentDate < iEndDate) Then
    Console.WriteLine("Current date is within the range.")
    'Other Codes here
Else
    Console.WriteLine("Current date is in the range.")
    'Other Codes here
End If

OR

Dim iObj As Object = IIf((iCurrentDate > iStartDate) And (iCurrentDate < iEndDate), "Current date is within the range.", "Current date is in the range.")
Console.WriteLine(iObj.ToString)
'Other Codes here

上面的代码有替代品吗？就像在SQL查询中的BETWEEN一样？

Answer 1

内置任何内容，但您可以使用扩展方法：

<Extension()> _
Public Function IsBetween(theDate As DateTime, minDate As DateTime, maxDate As DateTime) As Boolean
    Return theDate > minDate AndAlso theDate < maxDate
End Function

然后你可以像这样使用它：

If iCurrentDate.IsBetween(iStartDate, iEndDate) Then
    Console.WriteLine("Current date is within the range.")
    'Other Codes here
Else
    Console.WriteLine("Current date is not in the range.")
    'Other Codes here
End If

或者像这样：

Console.WriteLine(If(iCurrentDate.IsBetween(iStartDate, iEndDate), _
                     "Current date is within the range.", _
                     "Current date is not in the range."))

Answer 2

不，.NET中没有BETWEEN运算符，你真的错过了吗？

注意：

你可以/ use IF instead of IIF。

Dim message = _ If((iCurrentDate > iStartDate) AndAlso (iCurrentDate < iEndDate), _ "Current date is within the range.", _ "Current date is not in the range.")

速度更快：第一部分仅在第一部分false评估时才会被评估，没有装箱/拆箱

它更安全：没有NullRefernceException，因为你已经忘记了上面

它更具可读性和类型安全性

Answer 3

没有直接的替代品，我已经看到了一些选择案例：

Select Case iCurrentDate
    Case iStartDate To iEndDate
        'is between
    Case Else
        'is not
End Select

我从未使用过类似的东西。我不确定它的起源是什么。我通常会使用AndAlso对代码进行一些修改：

   If (iCurrentDate > iStartDate) AndAlso (iCurrentDate < iEndDate) Then
            Console.WriteLine("Current date is within the range.")
            'Other Codes here
        Else
            Console.WriteLine("Current date is in the range.")
            'Other Codes here
        End If

VBNet日期比较

3 个答案: