Convert Atom-formatted DateTime

The following function converts ATOM (RFC4287) formatted Date/Time string into a VBScript Date variable. You’ll find it useful if you want to process Atom feeds with VBScript/ASP.

Function AtomDateTime(S)
  Dim CompArray,ValueArray,DateVal,TimeString,TimeVal,ZoneSign,ZoneString,I

  CompArray = Split(S,"T")
  If UBound(CompArray) <> 1 Then _
    Err.raise vbObjectError,"AtomDateTime","No 'T' in Atom date/time"
  ValueArray = Split(CompArray(0),"-")
  If UBound(ValueArray) <> 2 Then _
    Err.raise vbObjectError,"AtomDateTime","Atom date part is not a date"
  DateVal = DateSerial(CInt(ValueArray(0)),CInt(ValueArray(1)),CInt(ValueArray(2)))

  TimeString = CompArray(1) : I = InStr(TimeString,"Z") 
  If I > 0 Then
    TimeString = Left(TimeString,I-1)
    TimeVal = GetAtomTime(TimeString)
  Else
    I = InStr(TimeString,"-")
    If I > 0 Then 
      ZoneSign = 1 
    Else
      ZoneSign = -1 : I = InStr(TimeString,"+")
    End If
    If I = 0 Then _
      Err.raise vbObjectError,"AtomDateTime","cannot recognize timezone separator"
    ZoneString = Mid(TimeString,I+1,Len(TimeString))
    TimeString = Left(TimeString,I-1)
    TimeVal = GetAtomTime(TimeString) + ZoneSign * GetAtomTime(ZoneString)
  End If
  AtomDateTime = DateVal + TimeVal
End Function 

The DateTime is converted into GMT time value. You might need to add/subtract your local timezone offset if you want to get local time.

The GetAtomTime function converts the time portion of the DateTime field:

Function GetAtomTime(TS) 
  Dim I : I = InStr(TS,".") : If I > 0 Then TS = Left(TS,I-1)
  GetAtomTime = Timevalue(TS)
End Function