[RESOLVED] [02/03] Passing Array of Structures to Functions

[mizxtara]

Everytime I try to debug this code, I get an error in the function saying that an instance of the object is not created. I really do not know why or what I am doing wrong. I stare, but I do not know what is wrong. I am not familiar with structures, but I am trying.

Const MAXSIZE As Integer = 25
    'MY STRUCTURE for the text file!
    Structure StudentData
        Dim name As String
        Dim ssn As String
        Dim numGrades As Double    'Gathers of the number of grades of each student
        Dim avg As Double
        Dim lg As String
    End Structure
    Dim student(MAXSIZE) As StudentData

    'The Choose Input File event procedure should be enabled so as the user clicks this button first, because a text file should be chosen.
    'This sub will collect the data in the input text file to the structure of the array and store them there in order to not waste IO. 
Private Sub btnChoose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnChoose.Click
        lstOutput.Items.Clear()     'The list box should be cleared before choosing a file.
        Dim count As Integer = 0        'Counter of the arrays and do-until loop.
        Dim recFile As System.IO.StreamReader       'To begin openning the file.

        'Set the filter of the OpenFileDialog control and specify the directory to be initially displayed.
        ofdReadFile.Filter = "Text files (*.txt)|*.txt|All Files (*.*)|*.*"
        ofdReadFile.InitialDirectory = "C:\Temp"

        'If the user selected a file, the filename is displayed. An if-statement is used to control this. Then a do-until loop is used to
        'collect the data until the end of the file is reached.
        If (ofdReadFile.ShowDialog = DialogResult.OK) Then
            recFile = System.IO.File.OpenText(ofdReadFile.FileName)
            Do Until recFile.Peek = -1
                Dim n As Double = 0      'n variable is for the for-loop to read the grades of each student.
                Dim total As Double = 0     'total variable is to help calculate the average of each student.
               
                student(count).name = recFile.ReadLine()
                student(count).ssn = recFile.ReadLine()
                student(count).numGrades = Val(recFile.ReadLine())
                For n = 1 To student(count).numGrades
                    total += Val(recFile.ReadLine)
                Next
                total /= student(count).numGrades
                student(count).avg = total
                student(count).lg = LetterGrade(student(count).avg)
                count += 1
            Loop
            recFile.Close()     'Close the file.
        End If
End Sub


'The FullName function takes the name of the student in the format "Last, First" and returns the name in the format "First Last".
    Function FullName(ByVal fn As String) As String
        'The nested if-statements are to validate the array name and if there is a comma in the full name.
        Dim comma, count As Integer
        Dim first As String
        Dim last As String

        If fn.Length > 0 Then         'THIS IS WHERE THE DEBUGGING STOPS ME.
            If fn.IndexOf(",") > 0 Then
                comma = fn.IndexOf(",")  'The comma variable is given the index of the comma value using the IndexOf method.
                first = fn.Substring(comma + 1).Trim
                last = fn.Substring(0, comma)
            End If
        End If

        Return first & " " & last   'Return the reformatted full name.
End Function


 Private Sub btnGenerate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGenerate.Click
        Dim count As Integer    'Declare counter for the arrays.

        'There will have to be a count loop here to show the list of names and info!!!
        For count = 0 To (student.Length - 1)
            lstOutput.Items.Add(String.Format("{0, -28}{1, -14}{2, -6}{3, -7}{4, -6}", FullName(StudentData), SSNum(student(count).ssn), _
            student(count).numGrades, student(count).avg, LetterGrade(student(count).avg)))
End Sub

There is more to the code, but this is what is surrounding my problem. If you need more questions about the purpose of this project, ask!