How to get start and end of previous month in VB

问题

Im trying to create some VB code that will get the start and end of the previous month. Im able to the current month which is just:

Month(DateValue(Now))

which would return 3. From there I can take away 1 to give me 2 meaning February. This is fine but what about when I Im in January and I repeat this and it gives me zero - my code will fail. Any one know how to get the previous months start and end day then?

Thanks

回答1:

The first day of the previous month is always 1, to get the last day of the previous month, use 0 with DateSerial:

''Today is 20/03/2013 in dd/mm/yyyy
DateSerial(Year(Date),Month(Date),0) = 28/02/2013 
DateSerial(Year(Date),1,0) = 31/12/2012

You can get the first day from the above like so:

LastDay = DateSerial(Year(Date),Month(Date),0)
FirstDay = LastDay-Day(LastDay)+1

See also: How to caculate last business day of month in VBScript

回答2:

I have similar formula for the First and Last Day

The First Day of the month

FirstDay = DateSerial(Year(Date),Month(Date),1)

The zero Day of the next month is the Last Day of the month

LastDay = DateSerial(Year(Date),Month(Date)+ 1,0)

回答3:

firstDay = DateSerial(Year(DateAdd("m", -1, Now)), Month(DateAdd("m", -1, Now)), 1)
lastDay = DateAdd("d", -1, DateSerial(Year(Now), Month(Now), 1))

This is another way to do it, but I think Remou's version looks cleaner.

回答4:

Try this

First_Day_Of_Previous_Month = New Date(Today.Year, Today.Month, 1).AddMonths(-1)

Last_Day_Of_Previous_Month = New Date(Today.Year, Today.Month, 1).AddDays(-1)

回答5:

This works reliably for me in my main sub.

Dim defDate1 As Date, defDate2 As Date

'** Set default date range to previous month
defDate1 = CDate(Month(Now) & "/1/" & Year(Now))
defDate1 = DateAdd("m", -1, defDate1)
defDate2 = DateAdd("d", -1, DateAdd("m", 1, defDate1))

回答6:

Try this to get the month in number form:

Month(DateAdd("m", -3, Now))

It will give you 12 for December.

So in your case you would use Month(DateAdd("m", -1, Now)) to just subract one month.

回答7:

Just to add something to what @Fionnuala Said, The below functions can be used. These even work for leap years.

'If you pass #2016/20/01# you get #2016/31/01#
Public Function GetLastDate(tempDate As Date) As Date
    GetLastDate = DateSerial(Year(tempDate), Month(tempDate) + 1, 0)
End Function

'If you pass #2016/20/01# you get 31
Public Function GetLastDay(tempDate As Date) As Integer
    GetLastDay = Day(DateSerial(Year(tempDate), Month(tempDate) + 1, 0))
End Function

回答8:

Public Shared Function GetFOMPrev(ByVal tdate As Date) As Date
    Return tdate.AddDays(-(tdate.Day - 1))
End Function

Public Shared Function GetEOMPrev(ByVal tdate As Date) As Date
    Return tdate.AddDays(-tdate.Day)
End Function

Usage:

'Get End of Month of Previous Month - Pass today's date
EOM = GetEOMPrev(Date.Today)

'Get First of Month of Previous Month - Pass date just calculated
FOM = GetFOMPrev(EOM)

来源：https://stackoverflow.com/questions/15430035/how-to-get-start-and-end-of-previous-month-in-vb

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