Function to get accurate years between two Gregorian dates (1 Viewer)

[Accessna]

Function GetYears(ByVal DateFm As Long, ByVal DateTo As Long) As Double
  Dim Leap004 As Long
  Dim Leap100 As Long
  Dim Leap400 As Long
  Dim LeapYears As Long
  Dim SmblYears As Long
  Dim Leap As Long
  Dim Smbl As Long
  Dim LeapFm As Long
  Dim SmblFm As Long
  Dim inDate As Long
  Dim yy As Integer
  
  'Years between 102 And 9999
  If DateFm < DateSerial(102, 1, 1) Or _
     DateTo < DateSerial(102, 1, 1) Then Exit Function
  
  If DateFm > DateTo Then
    inDate = DateFm
    DateFm = DateTo
    DateTo = inDate
  End If
  '------------------
  DateFm = DateFm - 1
  '------------------
  inDate = DateFm
  GoSub Calculate
  LeapFm = Leap
  SmblFm = Smbl
  '------------------
  inDate = DateTo
  GoSub Calculate
  Leap = Leap - LeapFm
  Smbl = Smbl - SmblFm
  '------------------
  GetYears = (Leap / 366) + (Smbl / 365)
  Exit Function
  '------------------
Calculate:
  yy = Year(inDate) - 1
  
  Leap004 = Fix(yy / 4)
  Leap100 = Fix(yy / 100)
  Leap400 = Fix(yy / 400)
  LeapYears = Leap004 - Leap100 + Leap400
  SmblYears = yy - LeapYears
  Leap = CLng(LeapYears * 366)
  Smbl = CLng(SmblYears * 365)
  
  '  Day(DateSerial(yy + 1, 3, 0))
  If Day(DateSerial(yy + 1, 3, 1) - 1) = 29 Then
    Leap = Leap + (inDate - DateSerial(yy, 12, 31))
  Else
    Smbl = Smbl + (inDate - DateSerial(yy, 12, 31))
  End If
  
  Return
End Function

 

[Galaxiom]

If you have done it right then you should get the same answer as the Access built in Datediff function.

Note however that neither your function nor DateDiff account for the dozens of shifts in the date as the Gregorian calendar was adopted by different countries between 1582 and 1923.

 

[Accessna]

Hi,
my English is weak, I hope you understand me.

- Datediff will not give same result of GetYears Function.
- This function for Gregorian Calendar only, not for the International Calendar which is compound between Julian & Gregorian.

Regards.

 

[Galaxiom]

- Datediff will not give same result of GetYears Function.

The only difference between your GetYears and DateDiff when calculating years is that you are returning a Double rather than a Long so GetYears can show the fractional parts of a year.

- This function for Gregorian Calendar only, not for the International Calendar which is compound between Julian & Gregorian.

There is no calendar difference. The calendar used by the DateDiff function is wholly Gregorian. As I pointed out in my first post, it does not account for the days that were skipped on the change from the Julian Calendar because this would required dozens of regional differences to be managed.