[RESOLVED] [2005] String Arrary comparison problem

[Abrium]

Hey guys,

I have a problem with the output I am receiving when I attempt to compare two arrays. It seems that output in lisResults just keeps looping even though I have it on a counter. I am going to alter after I post this but I'm not quite sure where I am going wrong here. Anyone spot something that look quite correct?

The two string arrays I am comparing each have a single character in each index that can be A thru D. If the same index of each array match I would like LisResults to add "Correct" at the same index. This isn't happening though.

        Dim ElementGrade As String
        Dim ElementAnswer As String
        Dim i As Integer



        For Each ElementGrade In GradeArray
            For Each ElementAnswer In AnswerArray
                For i = 0 To 19
                    If GradeArray(CInt(ElementGrade)) = AnswerArray(CInt(ElementAnswer)) Then
                        Display.LisResults.Items.Add("correct")
                    Else
                        Display.LisResults.Items.Add("incorrect")

                    End If
                Next
            Next
        Next

        Display.ShowDialog()

OK figured out why LisResults was severly spamming creating a huge index. I replaced the code above with the following code:

        Dim i As Integer



        For i = 0 To 19
            If GradeArray(i) = AnswerArray(i) Then
                Display.LisResults.Items.Add("correct")
            Else
                Display.LisResults.Items.Add("incorrect")
            End If
        Next

My problem now however is that LisResults is constantly adding "correct" to the index because according to the code above the index of GradeArray and AnswerArray are always going to equal each other because they are on the same counter. When I need to do is access and compare the value inside the given index of each array.

[jmcilhinney]

You've got three loops there. If there were 20 elements in each arrays your If statement would be executed 8000 times. Is that really what you want? I think not.

Are you saying that you have two arrays, each with 20 elements, and you want to compare the elements at corresponding indices in each? If so then you should only have one loop:

For i As Integer = 0 To GradeArray.GetUpperBound(0) Step 1
    If GradeArray(i) = AnswerArray(i) Then
        'Correct.
    Else
        'Incorrect.
    End If
Next i

[Abrium]

Yes I have two arrays, and I edited my post because you were right, as I would looking at it I realized that I had three nested loops... not a good thing. I altered the code now its just the value at the indices

[Abrium]

I have the following code at this point but it doesn't seem to be pulling the value at the indices, it seems to be working off of the index itself.

        For i = 0 To 19
            If GradeArray(i) = AnswerArray(i) Then
                Display.LisResults.Items.Add("correct")
            Else
                Display.LisResults.Items.Add("incorrect")
            End If
        Next

[jmcilhinney]

That code will do exactly what it looks like it would do: compares each element of GradeArray to the element of AnswerArray at the same index.

[Abrium]

Thats what I thought. I need to find the error then because if I run the code and completely zero out GradeArray the display form still shows a "correct" indicating a right answer when there isn't an answer at all.

[Abrium]

This is starting to make me mad. Why the #$&^ is this returning the indices instead of the values of the indices??

        count = 0
        For count = 0 To GradeArray.Length - 1
            GradeArray(count) = _
            CStr(Display.LisResults.Items.Add(GradeArray(count)))
        Next

[stimbo]

Bit of a silly question but are you 100% sure you have got the correct values into the arrays? Just as a test what happens if you do:

MessageBox.Show("Testing Grade 0: " & GradeArray(0).ToString & " Answer Array 0 is: " & AnswerArray(0).ToString)

This bit of code doesn't really make much sense, not that it would cause too many problems.

GradeArray(count) = _
            CStr(Display.LisResults.Items.Add(GradeArray(count)))

[Abrium]

I have the values correct in two arrays. One I declared, another is filled by an if... then statement but I just can not get these two arrays to compare, going on two days and still charging at it. I'll keep yall updated, if you think of something by all means share.

[jmcilhinney]

Have you placed a break point on this line:

If GradeArray(i) = AnswerArray(i) Then

then added GradeArray(i) and AnswerArray(i) to the Watch window, then stepped through the code? That's how you debug: watch your code in action. Only then can you know exactly what it's doing an why.

[Abrium]

I have solved the problem, not the way I would of liked to to be honest. Instead of attempting to compare the arrays which have caused me all of this head ache to begin with I just used the information stored @ each indices of the listboxes I used to show output, I ended up using this code and it seems to work fine. I'm going to debug it a few times to search for mathematical exceptions but I'm sure its on the up and up.

final code(array free )

        For counter = 0 To 19
            If Display.LisAnswers.Items(counter) Is _
            Display.LisCorrect.Items(counter) Then
                Display.LisResults.Items.Add("right")
            Else
                Display.LisResults.Items.Add("wrong")
            End If
        Next

I just need more time/experience with arrays and the way they populate and can be evaluated with the use of a counter. You bring up a very good point also, I should of debugged it in the begining and we see where NOT doing that has put me a day behind just punching in and figuring its going to work... lol I could of been done with this already but at least its solved.