How to get correct answer for quiz when randomly assigning answers, from a dataset, to a buttons text attribute

Question

I have a quiz that I'm writing and I'm using 4 buttons text attributes to display the multiple choice answers. 1 is correct, the other 3 are wrong.

The answers are from my dataset and then randomly assigning the answers to the buttons text attributes, when the user selects an answer then it moves along to the next question and doing the same thing, as it should.

But what I can't seem to figure out is, since I'm assigning the answers randomly, how do I keep track of answer that was selected? Here is the code...

Label1.Text = ds.Tables[0].Rows[myNum]["Question"].ToString();
string[] array = new string[4] {
    ds.Tables[0].Rows[myNum]["CorrectAnswer"].ToString(),
    ds.Tables[0].Rows[myNum]["WrongAnswer1"].ToString(),
    ds.Tables[0].Rows[myNum]["WrongAnswer2"].ToString(), 
    ds.Tables[0].Rows[myNum]["WrongAnswer3"].ToString(),
};



// randomize the ordering of the items
System.Random rnd = new System.Random();
array = array.OrderBy(x => rnd.Next()).ToArray();

// each time you run this, the correct answer will be in a different place:
btn1.Text = array[0];
btn2.Text = array[1];
btn3.Text = array[2];
btn4.Text = array[3];


myNum = myNum + 1;

if (myNum == numOfRows)
   Response.Redirect("~/Results.aspx");

I have tried this...

ds.Tables[0].Rows[myNum]["CorrectAnswer"].ToString() + "1",
ds.Tables[0].Rows[myNum]["WrongAnswer1"].ToString() + "0",
ds.Tables[0].Rows[myNum]["WrongAnswer2"].ToString() + "0", 
ds.Tables[0].Rows[myNum]["WrongAnswer3"].ToString() + "0",

and as expected it didn't work at all, but I tried it any ways.

Any ideas?

Thanks

Answer 1

When you shuffle your array you lose track of the correct solution. This is not what you want. You should always be able to tell from your code which button will be assigned the correct answer. This does not mean you should know which id this button has, but how it gets assigned.

One thing you could do for example is shuffle an array of your button objects, and always assign your correct answer to the first index in that array.

So you create an array of your button objects, shuffle it. You assign the correctAnswerClick handler and the answer string to the first index (0) in that array. You assign the falseClick and wrong answers to index 1, 2 and 3. This way you always know that the correct button has the proper event handler.

The code below is what you want to achieve in Winforms (I don't have ASP installed in VS.Net atm) but it should be easily translated to ASP.Net I think.

button1 to button4 are named btn1 to btn4 in your case.

public partial class Form1 : Form
{

    private void Form1_Load(object sender, EventArgs e)
    {
        var btnns = new List<Button>();
        btnns.Add(button1);
        btnns.Add(button2);
        btnns.Add(button3);
        btnns.Add(button4);

        //Shuffle the list
        Shuffle<Button>(ref btnns);

        //Add an event handler for success to your first button
        btnns[0].Click += successClick;
        btnns[0].Text = "Correct";

        for (int i = 1; i < btnns.Count; i++)
        {
            btnns[i].Click += failedClick;
            btnns[i].Text = "Wrong " + i;
        }


    }
    private void failedClick(object sender, EventArgs e)
    {
        //Add a true value to the viewstate list
            AddAnswer(true);
    } 
    private void successClick(object sender, EventArgs e)
    {
        //Yay, it's correct
        AddAnswer(false);
    }
    public void AddAnswer(bool correctornot)
    {
           //I am not 100% sure about the code below (not tested), but it should give you an idea
           if (Session["listOfAnswers"] != null)
           {
                var currentList = (List<bool>) Session["listOfAnswers"];
                currentList.Add(correctornot);
                Session["listOfAnswers"] = currentlist;
           }
           else
           {
               var currentlist = new List<bool>();
               currentlist.Add(correctornot);
               Session["listOfAnswers"] = currentlist;
            }
    }
    public void Shuffle<T>(ref List<T> list)
    {
        Random rng = new Random();
        int n = list.Count;
        while (n > 1)
        {
            n--;
            int k = rng.Next(n + 1);
            T value = list[k];
            list[k] = list[n];
            list[n] = value;
        }
    }
}

Answer taken from here: Randomize a List<T>