How to choose a random case in a switch statement

Question

I want to output several questions, but in a random order. How can I ask all questions randomly without repeating one?

for(int i=0; i<4; i++)
{
    int question=rand()%4;
    switch(question)
    {
        case 0:
            NSLog(@"What is your name");
            break;
        case 1:
            NSLog(@"Who are you");
            break;
        case 2:
            NSLog(@"What is your name");
            break;
        case 3:
            NSLog(@"How do you do");
            break;
        case 4:
            NSLog(@"Are you?");
            break;
    }
}

Are you asking how to remove the `for` loop from the `switch`? — Josh, Aug 01 '11 at 20:49
Just a tip: putting "Random question" as the question title is probably not a good idea because it sounds like you're just asking some random question. Something like "how to choose a random case in a switch statement" might have been better. — mgalgs, Aug 01 '11 at 22:46

score 5 · Accepted Answer · answered Aug 01 '11 at 20:52

5

Keep the questions in an array. Shuffle the array at the start of questioning. Now pull one question from the list per iteration, ask it, get the answer, and continue until you run out of questions.

answered Aug 01 '11 at 20:52

Marvo

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Upon further reading, I think this is a better answer - the OP's question is pretty vague, but this answer might be the one he's looking for. – Carl Norum Aug 01 '11 at 20:54
1

@Josh@Joe@Carl Norum Thank yu for your attention to me – NCFUSN Aug 01 '11 at 22:17

score 4 · Answer 2 · answered Aug 01 '11 at 20:50

rand(3) is pretty famous for having poor implementations that have pretty short cycles for the lower bits. Try using different bits, or use random(3) instead. In fact, the rand(3) man page on OS X says:

These interfaces are obsoleted by random(3).

Also - % 4 can never be larger than 3, so your case 4 will never execute in this program.

score 1 · Answer 3 · edited May 23 '17 at 12:26

1

It is recommended to use arc4random() for a better algorithm with out the need to seed. Otherwise call srand to seed your call to rand.

edited May 23 '17 at 12:26

Community

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answered Aug 01 '11 at 20:49

Joe

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Thanks for this useful information, but is the any method to avoid repeats completely? – NCFUSN Aug 01 '11 at 20:52
1

Nathan - I think @Marvo's answer hit what you're looking for. – Carl Norum Aug 01 '11 at 20:57
@Carl Norum I agree with you as that is probably the expected results. – Joe Aug 01 '11 at 20:59

How to choose a random case in a switch statement

3 Answers3