Tom Windows

As everyone knows, VBScript blows. However, on occassion, we sometimes are forced to work in it. One significant limitation is that VBScript does not provide a function to format dates with any arbitrary date format string. There are a number of solutions on the net but I have discovered one that provides significantly more power since it leverages the .NET Framework.

Public Function FormatDate( dDateValue, sFormat )
'PURPOSE: To format a date with any arbitrary format
'ARGS:
'   sFormat is the defined formats as used by the .NET Framework's System.DateTimeFormatInfo.
'       Note that this format is case-sensitive.
'CALLS:
'   1. System.Text.StringBuilder class in the .NET Framework.
'EXAMPLE CALL:  
'   Dim sFormatedDate
'   sFormatedDate = FormatDate( "1/1/1900 12:00 AM", "MM/dd/yy" )
'   Or
'   sFormatedDate = FormatDate( "1/1/1900 12:00 AM", "MM/dd/yyyy" )
'DESIGN NOTE:
'   This function leverages the fact that System.Text.StringBuilder is COMVisible.
'   Thus, we can call its AppendFormat function from here.
'   You can find more information about the format string parameters allowed at
'   http://msdn.microsoft.com/en-us/library/system.globalization.datetimeformatinfo.aspx

    Dim oStringBuilder
    Dim sSbFormatString

    If Not IsDate( dDateValue ) Then
        FormatDate = vbNullString
        Exit Function
    End If    
    
    'if an empty format string is passed, then simply return
    'the value using the default shortdate format.
    If Len(sFormat & vbNullString) = 0 Then
        sSbFormatString = "{0:d}"
    Else
        sSbFormatString = "{0:" & sFormat & "}"
    End If
    
    sSbFormatString = "{0:" & sFormat & "}"
    Set oStringBuilder = CreateObject("System.Text.StringBuilder")
    FormatDate = oStringBuilder.AppendFormat(sSbFormatString, dDateValue)
    Set oStringBuilder = Nothing
End Function

.NET Development, Unintended Consequences