### DATEDIFF(interval, date1, date2 [,firstdayofweek] [,firstweekofyear])

Returns the number of a given time interval between two specified dates (Long).

 interval The interval of time you want to calculate (String):"yyyy","YYYY" = year"q","Q" = quarter"m","M" = month"y","Y" = day of year"d","D" = day"w","W" = weekday"ww","WW" = week"h","H" = hour"n","N" = minute"s","S" = second date1 The start date (Date). date2 The finish date (Date). firstdayofweek (Optional) A vbDayOfWeek constant that specifies the first day of the week:0 = vbUseSystemDayofWeek1 = vbSunday (default)2 = vbMonday3 = vbTuesday4 = vbWednesday5 = vbThursday6 = vbFriday7 = vbSaturday firstweekofyear (Optional) A vbFirstWeekOfYear constant that specifies the first week of the year:0 = vbUseSystem1 = vbFirstJan1 (default)2 = vbFirstFourDays3 = vbFirstFullWeek

 REMARKS
 * If "date1" or "date2" are enclosed in double quotation marks and the year is not entered then the current year is used.* If "date1" > "date2" then a negative number is returned.* If "firstdayofweek" is left blank, then 1 is used (ie Sunday).* If "firstweekofyear" is left blank, then the first week is assumed to be the week in which January 1 occurs.* The "firstdayofweek" is only relevant if the "interval" is either "w" or "ww".* This function can be used to determine how many specified time intervals exist between two dates.* You can use the DATEDADD function to return the date with a specified time interval added.* You can use the DATEPART function to return the specified part of a given date.* The equivalent .NET function is Microsoft.VisualBasic.DateAndTime.DateDiff* For the Microsoft documentation refer to docs.microsoft.com

`Debug.Print DateDiff("d",Date(), "31/12/2004",2,0) = ?? Debug.Print DateDiff("yyyy","31 Dec 2003","1 Jan 2004") = 1 ?? Debug.Print DateDiff("d", #12/1/2001#, #12/1/2000#, 0, 0) =   '2000 is a leap year so Feb has 28 days  `