Identically shuffle multiple arrays

Question

I am making a quiz game. I need to shuffle the arrays so that the questions, options, and answer arrays don't appear in order.

Here are the three arrays.

public string[] EasyQuestions = 
{
    "What is the capital of Australia?",
    "Who was Steve Jobs?",
    "What number Apollo took Neil Armstrong to the moon?",
    "Which metal is heavier, silver or gold?",
    "What country has the largest population?"
};

public string[] EasyOptions = 
{
    "Brisbane |Canberra |Adelaide |Australian Capital Territory",
    "CEO of Microsoft |Co-founder of Apple |Creator of IBM |Australian Politician",
    "10|11|12|1",
    "Silver|Gold|Gold|Silver",
    "'Murica|China|India|Australia"
};

public string[] EasyAnswers = 
{
    "Canberra",
    "Apple",
    "11",
    "Gold",
    "China"
};

I want all of the arrays to be shuffled identically so I don't get wrong answers with different options and different questions?

Perhaps you should look at creating classes for these things to make it easier on yourself. — Evan Trimboli
– Evan Trimboli, Commented Sep 20, 2013 at 2:49
I agree, make a QuizEntry class that has Question, Options, and Answer properties. Instantiate instances of this class, assign the values, throw them into a collection, then it becomes trivial to shuffle them. — Chris Sinclair
– Chris Sinclair, Commented Sep 20, 2013 at 2:52
How could I achieve this, any links. I thought of doing this, but had no idea how and what it is exactly called, I've only been programming for 6 months xD — Trontor
– Trontor, Commented Sep 20, 2013 at 2:55
@Trontor: Creating classes is a fundamental, basic part of C#. google.ca/#q=C%23+class+tutorial — Chris Sinclair
– Chris Sinclair, Commented Sep 20, 2013 at 2:57
@Trontor: If you want random order, then yes, you still have to shuffle. But you don't have to shuffle three arrays -- just one -- so keeping stuff in sync becomes a non-issue. — cHao
– cHao, Commented Sep 20, 2013 at 4:15

Evan Trimboli · Accepted Answer · 2013-09-20 02:53:41Z

4

As I suggested in the comment, if you group everything together then you don't need to worry about keeping things in sync:

public class Question {

    private List<string> answers;

    public Question(string text, IEnumerable<string> answers, int answer) {
        this.Text = text;
        this.Answer = answer;

        this.answers = new List<string>(answers);
    }

    public string Text {
        get;
        private set;
    }

    public int Answer {
        get;
        private set;
    }

    public IEnumerable<string> Answers {
        get {
            return this.answers;
        }
    }

    public string GetAnswer() {
        return this.answers[this.Answer];
    }
}

answered Sep 20, 2013 at 2:53

Evan Trimboli

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3 Comments

Trontor Over a year ago

Ahh, so this is how you do properties and such. Even though this doesn't directly answer my question, it is greatly appreciated.Thanks

Trontor Over a year ago

Could you mind explaining how this eliminates the need of shuffling?

Evan Trimboli Over a year ago

It doesn't, if you want to randomize it you'd still need to shuffle the collection, but you only have to shuffle a single collection. Then you also have the added benefit of having a logical data structure, instead of having a few disparate arrays, one with pipe separated values (gross).

Zong · Accepted Answer · 2013-09-20 04:08:16Z

3

Use Fisher-Yates shuffle. It shuffles the elements in a single pass.

Random rnd = new Random();

for (int i = 0; i < EasyQuestions.Length - 1; i++) {
    int j = rnd.Next(i, EasyQuestions.Length);

    string temp = EasyQuestions[j];
    EasyQuestions[j] = EasyQuestions[i];
    EasyQuestions[i] = temp;

    temp = EasyOptions[j];
    EasyOptions[j] = EasyOptions[i];
    EasyOptions[i] = temp;

    temp = EasyAnswers[j];
    EasyAnswers[j] = EasyAnswers[i];
    EasyAnswers[i] = temp;
}

edited Sep 20, 2013 at 4:08

answered Sep 20, 2013 at 2:52

Zong

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3 Comments

Trontor Over a year ago

Thanks, this answered my question, so I'll mark it as the answer.

Trontor Over a year ago

What is the images array...?

Zong Over a year ago

Sorry, should be any of your arrays.

musical_coder · Accepted Answer · 2013-09-20 02:53:29Z

0

Don't shuffle the arrays themselves. Instead, shuffle a list of integers containing 0 through 4. Since this appears to be homework I'll let you figure out how to then use that shuffled list.

answered Sep 20, 2013 at 2:53

musical_coder

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1 Comment

Trontor Over a year ago

It isn't homework, I self-teach myself programming (Year 9), programming isn't part of our curriculum 8)

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