c# - Index was outside the bounds of the array?

Question

I keep getting this message "System.IndexOutOfRangeException: Index was outside the bounds of the array." when attempting to run a program I built, that utilized an exception catcher.

class StudentS { private List theStudentList;

    public bool PopulateStudents(string path)
    {
        theStudentList = new List<Student>();
        bool flag = false;
        try
        {
            List<string[]> strArrayList = new List<string[]>();
            using (StreamReader streamReader = new StreamReader(path))
            {
                string str;
                while ((str = streamReader.ReadLine()) != null)
                {
                    string[] strArray = str.Split(',');
                    strArrayList.Add(strArray);
                }
            }
            for (int index1 = 0; index1 < strArrayList.Count; ++index1)
            {
                string[] strArray = strArrayList[index1];
                Student student = new Student(strArray[0], strArray[1], strArray[2]); **where the error is**
                int index2 = 3;
                while (index2 < strArray.Length)
                {
                    student.EnterGrade(int.Parse(strArray[index2]), int.Parse(strArray[index2 + 1]));
                    index2 += 2;
                }
                student.CalGrade();
                theStudentList.Add(student);
            }
        }
        catch (Exception e)
        {
            flag = true;
            Console.WriteLine(e);
        }
        return flag;
    }

    public int ListLength
    {
        get
        {
            return theStudentList.Count;
        }
    }

    public float StudentAverage(int index)
    {
        return theStudentList.ElementAt(index).Average;
    }

    public string StudentGrade(int index)
    {
        return theStudentList.ElementAt(index).LetterGrade;
    }

    public string StudentID(int index)
    {
        return theStudentList.ElementAt(index).ID;
    }

    public string StudentLastName(int index)
    {
        return theStudentList.ElementAt(index).NameLast;
    }
}

class Student
{
    private float average;
    private ArrayList Earned;
    private string letterGrade;
    private string nameFirst;
    private string nameLast;
    private ArrayList Possible;
    private string studentID;

    public Student(string id)
    {
        studentID = null;
        nameFirst = null;
        nameLast = null;
        Earned = new ArrayList();
        Possible = new ArrayList();
    }

    public Student(string id, string first)
    {
        studentID = id;
        nameFirst = null;
        nameLast = null;
        Earned = new ArrayList();
        Possible = new ArrayList();
    }

    public Student(string id, string first, string last)
    {
        nameFirst = first;
        nameLast = last;
        studentID = id;
        Earned = new ArrayList();
        Possible = new ArrayList();
    }

    public float Average
    {
        get
        {
            return average;
        }
    }

    public string ID
    {
        get
        {
            return studentID;
        }
    }

    public string LetterGrade
    {
        get
        {
            return letterGrade;
        }
    }

    public string NameFirst
    {
        get
        {
            return nameFirst;
        }
        set
        {
            nameFirst = value;
        }
    }

    public string NameLast
    {
        get
        {
            return nameLast;
        }
        set
        {
            nameLast = value;
        }
    }

    public void CalGrade()
    {
        int num1 = 0;
        int num2 = 0;
        foreach (int num3 in Earned)
            num1 += num3;
        foreach (int num3 in Possible)
            num2 += num3;
        average = num1 / (float)num2;
        average = (float)Math.Round(average, 2);
        if (average >= 0.9)
            letterGrade = "A";
        if (average >= 0.8 && average < 0.9)
            letterGrade = "B";
        if (average >= 0.7 && average < 0.8)
            letterGrade = "C";
        if (average >= 0.6 && average < 0.7)
            letterGrade = "D";
        if (average >= 0.6)
            return;
        letterGrade = "U";
    }

    public void EnterGrade(int earnedValue, int possValue)
    {
        Earned.Add(earnedValue);
        Possible.Add(possValue);
    }
}

I am unsure as to what I have done wrong. Thanks for any help!

Edit: I went ahead and added a majority of the code here, in hopes that this answers your questions better. The data set I am dealing with is 4 rows, that are grabbed into the student array.

Answer 1

index2 + 1 may be out of range in the expression strArray[index2 + 1] below:

while (index2 < strArray.Length)
{
    student.EnterGrade(int.Parse(strArray[index2]), int.Parse(strArray[index2 + 1]));
    index2 += 2;
}

To process two elements at a time, use index2 < strArray.Length - 1