Loop Return retval。ToString（） End Function 。 。 。 End Class ■Note In the downloadable source code； the individual steps taken to clean up the data stream are demon strated。 For reference； the intermediate development steps in the source code are called Process01（） through Process05（）。 Let’s review how this code fixes the five problems we discovered。 …………………………………………………………Page 289…………………………………………………………… CH A PT E R 1 0 ■ L E A R N I N G A B O U T P E R S IS T E N CE 267 Empty Lines of Text The following code removes the empty lines of text。 If splitUpText（0）。Length = 0 Then Continue Do End If When lotto。txt was processed； the output data stream generated a single field array for an empty line。 So； we know that if the first field element has a length of zero； the line of text should be ignored。 Empty Fields and Too Many Fields The next problem in our list is that some lines have empty text fields at the end。 Solving this problem would probably entail a solution similar to the previous one； but you should think of the big picture and understand that solving one problem might also solve another problem。 In this case； solving the problem of the empty fields also helps solve the problem of having too many fields。 Both of these problems are solved by knowing the data that is being manipulated。 As you’ve seen； the data stream assumes the following format： date； then lottery numbers 1 to 6； and then the bonus number。 The parts of the data stream that are not correct have the same format； with some extra information like replay number and empty fields。 Thus； the fix is to copy the date and append the remaining fields； as follows： retval。Append（newDate） For c1 As Integer = 0 To 7 retval。Append（〃 〃 & splitUpText（c1）） Next The first line of code appends the date to the StringBuilder buffer （retval）。 Then in the For loop that follows； a space and the fields 0 to 7 are copied to the StringBuilder buffer。 Incorrect Data Format In some of the fields； the date has a period separator； in others； it has a hyphen。 The correct format is a period； and the code that fixes the date format is as follows： If splitUpText（0）。Contains（〃…〃） Then Dim dateSplit As String（） = splitUpText（0）。Split（New Char（） ｛〃…〃c｝） Dim newDate As String = dateSplit（0） & 〃。〃 & dateSplit（1） & 〃。〃 & dateSplit（2） A fix is needed if the first field contains a hyphen。 The If statement tests for this using the Contains（） method。 If a fix is needed； the first field is separated again into three subfields； where each subfield represents a part of the date （year； month； day）。 Then those three subfields are rebined and separated using the period and assigned to the variable newDate。 Duplicate Dates The last problem that needs to be solved is having duplicate dates in the data stream。 The following code fixes this problem （the duplicate date code is bolded）。 …………………………………………………………Page 290…………………………………………………………… 268 CH AP T E R 1 0 ■ L E A R N I N G A B OU T P E R S IS TE N CE If _dates。Contains（splitUpText（0）） Then Continue Do End If If splitUpText（0）。Length = 0 Then Continue Do End If If splitUpText（0）。Contains（〃…〃） Then Dim dateSplit As String（） = splitUpText（0）。Split（New Char（） ｛〃…〃c｝） Dim newDate As String = _ dateSplit（0） & 〃。〃 & dateSplit（1） & 〃。〃 & dateSplit（2） If _dates。Contains（newDate） Then Continue Do End If _dates。Add（newDate） retval。Append（newDate） For c1 As Integer = 0 To 7 retval。Append（〃 〃 & splitUpText（c1）） Next Else _dates。Add（splitUpText（0）） retval。Append（lineOfText） End If Of all the problems we needed to solve； this is the trickiest； because it required multiple pieces of code in multiple places。 The code processes the data stream and keeps a list of dates。 A date is added to the list only if the date does not exist in the list； which is checked using the Contains（） method。 The lists expose this method to verify if the object being passed to it equals one of the list members。 The way that most lists implement the method is to iterate each method and call the Equals（） method。 The catch is that if you declare a custom type； the Equals（） method defaults to verifying if one reference value equals another。 You would need to imple ment a custom Equals（） method。 ■Note When you encounter situations where you need to write multiple pieces of code in multiple places； that is a sign that you are about to create code that is hard to maintain。 You should take a close look at the code； and If possible； rewrite it。 Of course； this depends on a lot of factors。 So sometimes； you will need to just write the code； test it； and hope that it works。 With the final solution； the console application TextProcessor is plete。 You could process lotto。txt and get a correctly formatted data stream。