Calculate the exact differences between 2 given dates

Calculate the exact differences between 2 given dates

• Vikasumit

  Like so. For both the first and the second year (or whatever largest scale you choose), subtract off the number of ticks from its minor units to the first occurrence of that largest scale value. In my case, subtract off the number of ticks from its minor units to midnight January 1 of that year. Compare the two values, and if the last value is smaller than the first, you should decrement the resultant largest scale by 1.
  
  protected float GrowthRate(float dtStartYrOA, float dtEndYrOA, float fCompoundedRate)
  {
  float retVal = 1;
  
  DateTime dtStartYr = DateTime.FromOADate(dtStartYrOA);
  DateTime dtEndYr = DateTime.FromOADate(dtEndYrOA);
  
  ushort iStartYr = 0, iEndYr = 0;
  if (
  dtEndYr - new DateTime(iEndYr = (ushort)dtEndYr.Year, 1, 1, 0, 0, 0)
  < dtStartYr - new DateTime(iStartYr = (ushort)dtStartYr.Year, 1, 1, 0, 0, 0)
  )
  --iEndYr;
  
  for (ushort i = (ushort)iStartYr; i <= iEndYr; ++i) retVal += retVal * fCompoundedRate;
  return retVal;
  }
  
  
  

• jcarlos.net

  DateDiff won't work, because according to the documentation:

  When comparing December 31 to January 1 of the immediately succeeding year, DateDiff for Year ("yyyy") returns 1 even though only a day has elapsed.

  Try this function. It could be faster, but it seems to work for the tests I have made for it (it assumes y comes after x):

  Public Sub DateSpace(ByVal x As Date, ByVal y As Date, ByRef years As Integer, ByRef months As Integer, ByRef days As Integer)
  x = x.Date
  y = y.Date

  years = y.Year - x.Year
  x = x.AddYears(years)
  If x > y Then
  x = x.AddYears(-1)
  years -= 1
  End If

  months = 0
  Do
  x = x.AddMonths(1)
  months += 1
  Loop While x <= y

  months -= 1
  x = x.AddMonths(-1)

  days = 0
  Do
  x = x.AddDays(1)
  days += 1
  Loop While x <= y

  days -= 1
  End Sub

  Example use:

  Public Sub Main()

  Dim y As Integer = 0, m As Integer = 0, d As Integer = 0

  DateSpace(#2/2/2000#, #1/1/2001#, y, m, d)
  Console.WriteLine("{0}y {1}m {2}d", y, m, d)

  DateSpace(#2/1/2000#, #1/1/2001#, y, m, d)
  Console.WriteLine("{0}y {1}m {2}d", y, m, d)

  DateSpace(#11/1/2000#, #1/1/2001#, y, m, d)
  Console.WriteLine("{0}y {1}m {2}d", y, m, d)

  DateSpace(#12/31/2000#, #1/1/2001#, y, m, d)
  Console.WriteLine("{0}y {1}m {2}d", y, m, d)

  DateSpace(#12/31/2000#, #12/31/2000#, y, m, d)
  Console.WriteLine("{0}y {1}m {2}d", y, m, d)

  DateSpace(#2/29/2000#, #3/1/2001#, y, m, d)
  Console.WriteLine("{0}y {1}m {2}d", y, m, d)

  Console.ReadKey()
  End Sub

  
  

• pvulcan

  Why make it so complicated Simply use: dtStartYr.AddTicks((dtEndYr - dtStartYr).Ticks)
  
  

• Abhishekbhadouria

  no idea if this would work, just a suggestion, when calculated your TimeSpan value, why dont you take the ticks and place that in the constructor of a new dateTime object Example:

  Dim dateTime1 as DateTime = DateTime.Now

  Dim dateTime2 as DateTime = DateTime.Now.AddYears(3)

  Dim diff as TimeSpan = dateTime2 - dateTime1

  Dim dateTimeDiff as new DateTime(diff.Ticks)

  
  
  

• Nep23

  Thanks for the advice! I will make changes right away. Also which code should I use in terms of performance... wise...
  

• madsurfman

  Thank you for a very useful post through I haven't tried it yet. Actually with the answers and all the research I done, I decided to write my own code and this is what I came up with:

  sDay = oDateTime.Day

  eDay = Now.Day

  sMonth = oDateTime.Month

  eMonth = Now.Month

  sYear = oDateTime.Year

  eYear = Now.Year

  tYears = eYear - sYear

  If eMonth >= sMonth Then

  tMonths = eMonth - sMonth

  Else

  tYears -= 1

  tMonths = (12 - sMonth) + eMonth

  End If

  If eDay >= sDay Then

  tDays = eDay - sDay

  Else

  tMonths -= 1

  tDays = (DateTime.DaysInMonth(sYear, sMonth) - sDay) + eDay

  End If

  Through, I don't know if it works for all cases. May be someone can give a say on that. (By the way it just compares between now and the given time)

  
  

• Mike Strobel

  This may not be of concern, but if this were to execute while the current month changed, you would be in trouble, because eDay would be 30 while eMonth would be 12, even though it's only Midnight on 12/1. Try this:

  With Now ' grab a copy of "Now" so we ignore any changes that happen

  eDay = .Day

  eMonth = .Month

  eYear = .Year

  End With

  
  

• canadian_coder

  Try using the built in function to calculate the difference!

  DateAndTime.DateDiff (DateInterval, DateTime, DateTime, FirstDayOfWeek, FirstWeekOfYear)

  
  

• Angel David Lara

  ahmedilyas wrote:

  no idea if this would work, just a suggestion, when calculated your TimeSpan value, why dont you take the ticks and place that in the constructor of a new dateTime object Example: Dim dateTime1 as DateTime = DateTime.Now Dim dateTime2 as DateTime = DateTime.Now.AddYears(3) Dim diff as TimeSpan = dateTime2 - dateTime1 Dim dateTimeDiff as new DateTime(diff.Ticks)

  First time I saw something like this! Thanks. I tried it and it seems to work as long as I subtract 1 from Year, Month, and Day!!

  Thanks again!

  
  

• Repi3

  Ti, yours is better because it doesn't have any loops.
  

• programmer01

  Try the "DateDiff" function. Look it up in Help. It should cover your need.

  
  

• danadanny

  I implemented it and tested it. This method will not get the exact differences because with the Ticks, it contains no information about the months and the years in between so when converted back to datetime it would not be accurate.

  I tried today when getting the differences between 11/26/2006 and 9/26/2006, it would returns 2 months 2 days. The margin of error is too large.

  I need a way to get pretty much "exact" differences taken into account leapyears, different no. of days in months, and such.

  
  

• Devin

  If it does, I probably not posting this but it doesn't because it would return in either totaldays, total... whatever not separately as I am looking for.

  Unless you tell me it can returns x years x months x days ....

  I think they should consider adding DateSpan or something like that

  
  

• PeterVrenken

  This stuff really helped, I've used it and I have a bug fix too...

  Take a From date of "05 Dec 2006 17:00" and a To date of "7 Dec 2006 05:00". The code as you currently have it gives 2 days. However if you look closer at the time it is only 1 day and 12 hrs. My fix is this if statement after days are calculated

  if (this.toDate.Hour < this.fromDate.Hour)

  {

  // Not a full day so subtract fom the calculated days

  this.calculatedWholeDays--;

  }

  HTH

  Pat

  
  
• Calculate the exact differences between 2 given dates