一些關于日期的實用函數

时　间:2008-08-12 17:01:42
作　者:umvsoft整理   ID：43  城市：江阴
摘　要:数據處理離不開日期處理，以前經常是每次用到又重寫一次函數，挺浪費時間的。現整理了一些關于日期的實用函數，大家參考。附件中也有代碼，供下載用。
正　文:

数據處理離不開日期處理，以前經常是每次用到又重寫一次函數，挺浪費時間的。現整理了一些關于日期的實用函數，大家參考。附件中也有代碼，供下載用。

Public Function IsLeapYear(YearNumber As Integer) As Boolean
    Dim dteLeapDay As Date
   
    ' if particular year is not leap year,
    ' dteLeapDay will become Mar-01
    dteLeapDay = DateSerial(YearNumber, 2, 29)
    IsLeapYear = (Month(dteLeapDay) = 2)
End Function

' Based on vdate, the function will return the
' first day of the month
Public Function FirstDayOfMonth(vdate As Date) As Date
    Dim intCurrDate As Integer ' current date
    intCurrDate = DatePart("d", vdate)
   
    ' Deduct intCurrDate - 1 days
    FirstDayOfMonth = DateAdd("d", -intCurrDate + 1, vdate)
End Function

' Calculate first day of the month (method two)
' This method is quite straightforward
Public Function FirstOfMonth(vdate As Date) As Date
    FirstOfMonth = DateSerial(DatePart("yyyy", vdate), DatePart("m", vdate), 1)
End Function

' Based on vdate, the function will
' return the last day of the month
Public Function LastDayOfMonth(vdate As Date) As Date
    ' Get the first day of the next month, and then deduct 1 day
    LastDayOfMonth = DateSerial(DatePart("yyyy", vdate), DatePart("m", vdate) + 1, 1) - 1
End Function

' The function will return the first day of the year based on vdate
Public Function FirstDayOfYear(vdate As Date) As Date
    FirstDayOfYear = DateSerial(Year(Date), 1, 1)
End Function

' The function will return the first day of the week, based on vdate
Public Function FirstDayOfWeek(vdate As Date) As Date
    Dim intWeekday As Integer
    intWeekday = Weekday(vdate, vbMonday)
   
    FirstDayOfWeek = DateAdd("d", -intWeekday + 1, vdate)
End Function

' The function will return the last day of the week, based on vdate
' Monday is the first day (assumed)
Function LastDayOfWeek(vdate As Date) As Date
    Dim intWeekday As Integer
    intWeekday = Weekday(vdate, vbMonday)
   
    LastDayOfWeek = DateAdd("d", -intWeekday + 1, vdate) + 6
End Function

' The function will return number of week days between two dates
Function NumberOfWeekdays(BeginDate As Date, EndDate As Date, IncludingFirstDay As Boolean) As Integer
    Dim intCounter As Integer
    Dim intMovingDate As Date
   
    intCounter = 0
   
    If IncludingFirstDay = True Then
        intMovingDate = BeginDate
    Else
        intMovingDate = BeginDate + 1
    End If
        
    Do While intMovingDate <= EndDate ' End date inclusive
        If Weekday(intMovingDate) <> vbSunday And Weekday(intMovingDate) <> vbSaturday Then
           intCounter = intCounter + 1
        End If
        
        intMovingDate = intMovingDate + 1
    Loop
   

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