Shared Function ShowDate(value as DateTime) as string
   if value<=DateValue("1900-1-1") then
      return ""
   else
       return FormatDateTime(value,DateFormat.ShortDate)
    end if
End Function 

  =code.ShowNumber(Fields!PurchCC.Value,3)

Shared Function ShowNumber(value as Double, digit as integer ) as string
   if value=0 then
      return ""
   else
       return FormatNumber(value, digit)
    end if
End Function