vba：日期函数返回“00:00:00”
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vba: date function returns "00:00:00"
提问by user2002774
My below code returns "00:00:00", if passed value "DateValue" is null
我下面的代码返回“00:00:00”，如果传递的值“DateValue”为空
vba:
VB：
Public Function forDate(ByVal DateValue As String) As Date
Dim DoDate As Date
If Not IsNull(DateValue) And DateValue <> "" Then
DoDate = CDate(FormatDateTime(DateValue, 1, 10))
forDate = DoDate
End If
End Function
How to handle when "DateValue" is null??? please suggest an answer.
“DateValue”为空时如何处理？？？请提出一个答案。
回答by Brad
setting a Dateto null is valid (i.e. will run without error) provided you use vbNulland not Null. Though it will return #12/31/1899#and not nullitself. You can check you date variable against that known null value later as being your pseudo null value.
将 a 设置Date为 null 是有效的（即运行时不会出错），前提是您使用vbNull而不是Null。虽然它会返回#12/31/1899#而不是null它自己。您可以稍后根据该已知空值检查日期变量作为伪空值。
Or you could set it to the minimum date DateSerial(100, 1, 1)which will return #1/1/100#
或者您可以将其设置为DateSerial(100, 1, 1)将返回的最小日期#1/1/100#
回答by SeanC
This will handle null and/or empty strings:
这将处理空和/或空字符串：
Public Function forDate(ByVal DateValue)
If IsDate(DateValue) Then
forDate = CDate(DateValue)
Else
forDate = CVErr(xlErrValue)
End If
End Function
Notice I have removed the definitions of the variables to allow NULL to be passed correctly. when used as a function in a spreadsheet, the function will return a #VALUE!error if a string that cannot be represented as a date is passed
请注意，我删除了变量的定义以允许正确传递 NULL。在电子表格中用作函数时，#VALUE!如果传递了无法表示为日期的字符串，则该函数将返回错误
Example results:
示例结果：
回答by Floris
I think the solution may be to declare the function with a variant parameter|
我认为解决方案可能是声明带有变体参数的函数|
Public Function forDate(DateValue)
When VBA converts NULL to String, it is no longer NULL...
当 VBA 将 NULL 转换为 String 时，它不再是 NULL...
回答by Floris
See the comments for solution
解决办法见评论
Public Function forDate(ByVal DateValue As String) As Date ' will only accept string parameter
End Function
' below function is a variant and can accept string , null
Public Function forDate(DateValue)
Dim DoDate As Date
If DateValue & "" <> "" Then 'this will handle null and empty string
Else
'will go here when null or empty string
DateValue = Null
End If
End Function
