OL97: How to Programmatically Find a User's Next Available Free Time (263459)

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If the alias cannot be resolved, the function returns the invalid date, 1/1/4501. This date is commonly used by Outlook to represent an empty date field. If you programmatically store this date in an Outlook field, the word "None" appears in the field's control.

If the current time period for the recipient is marked as "free," the function returns the time that marked the beginning of the period, which is most likely in the past. For instance, if the current time is 1:43 PM and the recipient is currently marked as "free," this function returns the current date and a time of 1:30:00 PM.

In this sample code, time periods are measured in 30 minute increments. You can change this by modifying the value that is assigned to the intSlotLength variable.

Variable data types are commented for compatibility with VBScript.

Function GetNextFreeTime(strAlias)     ' As Date
    Dim olApplication   ' As Outlook.Application
    Dim olSession       ' As Outlook.NameSpace
    Dim olRecipient     ' As Outlook.Recipient
    Dim intSlotLength   ' As Integer
    Dim strFreeBusy     ' As String
    Dim intCurrentSlot  ' As Integer
    Dim intFreeSlot     ' As Integer
    Dim dblFreeSlot     ' As Double
    Dim dtmFreeSlot     ' As Date

    'get a reference to the Outlook session
    Set olApplication = CreateObject("Outlook.Application")
    Set olSession = olApplication.Session
    
    'get a reference to the recipient
    Set olRecipient = olSession.CreateRecipient(strAlias)
    olRecipient.Resolve

    'if the alias did not resolve, return an invalid date.
    If Not olRecipient.Resolved Then
        GetNextFreeTime = #1/1/4501#
        Exit Function
    End If

    'get the free busy string
    intSlotLength = 30
    strFreeBusy = olRecipient.FreeBusy(Date, intSlotLength, True)
    
    'calculate the position of *now* in the free busy string
    intCurrentSlot = Int(DateDiff("n", Date, Now) \ intSlotLength) + 1

    'get the position of next *free* in the free busy string
    intFreeSlot = InStr(intCurrentSlot, strFreeBusy, "0")
    
    'get the number of minutes into the day for my free slot
    dblFreeSlot = (intFreeSlot - 1) * intSlotLength
    
    'get an actual date/time
    dtmFreeSlot = DateAdd("n", dblFreeSlot, Date)
    GetNextFreeTime = dtmFreeSlot
End Function
				

To use the function, you need to supply the alias of the recipient. You can also supply a resolvable e-mail address or display name. The following line of sample code shows how to display the next free time period in a message box for the current user (where objOutlookNameSpace is a valid Outlook NameSpace object).

MsgBox GetNextFreeTime(objOutlookNameSpace.CurrentUser.Address)