List<Radio Buttons> in my C# program causes errors? Index always out of range?

For my program I am creating a register system to mark attendance for students. I start by taking the students in list student and creating a panel for each with an accompanying name textbox.

the next step is to add 3 radio buttons to each panel however it doesn’t seem to work as intended and I don’t know why. Can you not use a list of RadioButtons in the way I have.

To cover any confusion the studentlist is a test at the moment with them being names 1 – 10 and with regards to the buttons one would resemble present, absent and the other late.

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }


    private void Form1_Load(object sender, EventArgs e)
    {
        for (int i = 0; i < 10; i++)
        {
            studentlist.Add(i.ToString());
        }
        drawregisterpanels();
    }
    List<string> studentlist = new List<string>();

    public void drawregisterpanels()
    {
        TextBox[] StudentNames = new TextBox[studentlist.Count];

        Panel[] RowOfChoice = new Panel[studentlist.Count];

        int width = 100;
        int height = 25;
        for (int k = 0; k < RowOfChoice.Length; k++)
        {
            StudentNames[k] = new TextBox
            {
                Text = studentlist[k],
                Size = new Size(width, height),
                Location = new Point(0, height * k),
            };
            RowOfChoice[k] = new Panel
            {
                Name = k.ToString(),
                Size = new Size(width, height),
                Location = new Point(StudentNames[k].Width, height * k),
                BackColor = Color.CadetBlue,
                BorderStyle = BorderStyle.Fixed3D,

            };

            RegisterPanel.Controls.Add(StudentNames[k]);
            RegisterPanel.Controls.Add(RowOfChoice[k]);
            addradiobuttons(k, RowOfChoice);

        }

    }

    List<RadioButton> RegisterStatusChoice = new List<RadioButton>();
    void addradiobuttons(int panelno,Panel[] RowOfChoice)
    {
        int Width = RowOfChoice[panelno].Width / 3;
        int Height = RowOfChoice[panelno].Height;

        for (int p = 0; p < 3; p++)
        {
            Console.WriteLine((panelno*3)+p);
            RegisterStatusChoice[(panelno * 3) + p] = new RadioButton
            {
                Size = new Size(Width, Height),
                Location = new Point(Width * p, 0),
                CheckAlign = ContentAlignment.MiddleCenter,
            };
            RowOfChoice[panelno].Controls.Add(RegisterStatusChoice[(panelno * 3) + p]);
        }

    }

}

As can be seen before the radio buttons are attempted to be added it works as intended

However I don’t know why this error occurs as the integers provided shouldn’t be out of the range

>Solution :

You need to add the RadioButtons to the list, you just initialize it but don’t add it. Note that a list is different to an array. If you initialize it with a capacity it’s still empty and you can’t access items at a given index. You are using the default constructor anyway that just creates an empty list with the default capacity(4). So you need to add them first.

So instead of:

RegisterStatusChoice[(panelno * 3) + p] = new RadioButton
{
    Size = new Size(Width, Height),
    Location = new Point(Width * p, 0),
    CheckAlign = ContentAlignment.MiddleCenter,
};
RowOfChoice[panelno].Controls.Add(RegisterStatusChoice[(panelno * 3) + p]);

use this:

RadioButton rb = new RadioButton
{
    Size = new Size(Width, Height),
    Location = new Point(Width * p, 0),
    CheckAlign = ContentAlignment.MiddleCenter,
};
RegisterStatusChoice.Add(rb);
RowOfChoice[panelno].Controls.Add(rb);