如何计算出当前日期属于定义时间段内的第几星期？

Function CalculateWeekNo(BeginDate,EndDate,InputDate)
dim wdate(500,8)
z=0
x=0
strlong=len(CStr(inputdate))-9
inputdate=cdate(left(CStr(inputdate),strlong))
for i=cdate(BeginDate) to cdate(EndDate)
    if inputdate=i then
    x=z
    Exit For
    end if
    if weekday(i)=7 then
    z=z+1
    end if   
next

CalculateWeekNo=x
end Function

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