Can someone fix this time subtractor to return negative value

[samvb]

this is the code which I found online and works great. I forgot its author but whoever you are, 10x but a lil help would be appreciated...

here is the code

'public variables
Const MSecInSec As Double = 1000
Const SecsInMin As Double = 60
Const MinsInHour As Double = 60
Const HoursInDay As Double = 24
Const SecsInDay As Double = HoursInDay * MinsInHour * SecsInMin
Const mSecMult As Double = 1 / (SecsInDay * MSecInSec)

private sub command1_click()

msgbox  ReturnTimeDifference("01:00:00:00","04:30:00:00")
msgbox  ReturnTimeDifference("04:00:00:00","01:30:00:00")


end sub


Public Function ReturnTimeDifference(ByVal smalltime As String, ByVal bigtime As String) As String
Dim TimeA As Date
Dim TimeB As Date
 Dim Res As Double
 Dim timeparts As Variant
 Dim timepartsb As Variant
 Dim ms As String
 Dim ms2 As String
 timeparts = Split(smalltime, ":")
 timepartsb = Split(bigtime, ":")
 ms = timeparts(3)
 ms2 = timepartsb(3)
 
ms = ms & String(3 - Len(ms), "0")
ms2 = ms2 & String(3 - Len(ms2), "0")
 


 
 TimeA = TimeSerialEx(timeparts(0), timeparts(1), timeparts(2), ms) '01:04:12.2
 TimeB = TimeSerialEx(timepartsb(0), timepartsb(1), timepartsb(2), ms2) '05:08:15.55

 Res = Format$((TimeB - TimeA) * SecsInDay, "0.00") 'RETURNS POSITIVE NO MATTER WHAT!

ReturnTimeDifference = Format$(Res / SecsInDay, "hh:nn:ss:") & _
 Round(Res - Fix(Res), 2) * 100 'avoids the decimal point

End Function

both return positive value. he had commented this line as "returns postive no matter what

 Res = Format$((TimeB - TimeA) * SecsInDay, "0.00") 'RETURNS POSITIVE NO MATTER WHAT!

but i can't seem to figure out which part of it makes Res positive always.

any tips?

[Rabbit]

The format 0:00 makes it return only positive numbers since it doesn't allow for the negative sign.

[samvb]

i thot about it and removed it and tweaked it but nothing changed. can u help me out a lil bit?

[Rabbit]

I don't know the formats it allows. You may have to look that up but you can try 0:00;-0:00.

[MikeTheBike]

Hi

As pointed out by Rabbit the Time format does not take account of the sign and only returns +ve values.
However, contrary to the statement in the code this line

Res = Format$((TimeB - TimeA) * SecsInDay, "0.00")

does return -ve values, so the only suggestion I have is adding this line to the bottom of the function

If Res < 1 Then ReturnTimeDifference = "-" & ReturnTimeDifference

??

MTB

[whodgson]

As JosAH has pointed out somewhere you may wish to research JD (for Julian day) where you can convert a date to JD then add (or subtract) the number of days and then convert the new JD back to date. This is simply done.