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

CodePudding user response：

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);