Trying to generate random numbers on iphone, get same number

Question

I'm trying to make a card game. I'm using the following code to draw a random card

iCard=random() % 55;

but icard is always starts out with 28. Seems like it gives back the numbers in the same order.

is there a way to get a diffrent random number each time the function is first called????

Sanford has a class on iOS development, the first project is a card game. It might help you out. http://www.stanford.edu/class/cs193p/cgi-bin/drupal/ — Joe Million, Jun 08 '14 at 23:09
Also duplicate of http://stackoverflow.com/questions/1449754/iphone-random-function-gives-me-the-same-random-number-everytime — rmaddy, Jun 08 '14 at 23:48

Arbitur · Accepted Answer · 2014-06-08T22:58:04.563

3

random() and rand() uses a seed and it is always the same seed sequence.

Use arc4random() it uses no seed and is 100% random

edited Jun 08 '14 at 22:58

answered Jun 08 '14 at 22:51

Arbitur

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Use `arc4random_uniform(X)` instead of `arc4random() % X`. – rmaddy Jun 08 '14 at 23:49

score 0 · Answer 2 · answered Jun 08 '14 at 22:47

0

Try with this code: int random = min + arc4random() % (max - min + 1);

answered Jun 08 '14 at 22:47

Julian F. Weinert

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score 0 · Answer 3 · answered Jun 08 '14 at 22:51

0

-(IMCard*) drawRandomCard
{
    IMCard *randomCard = nil;

    if ([self.cards count]) {
        unsigned index = arc4random() % [self.cards count];
        randomCard = self.cards[index];
        [self.cards removeObjectAtIndex:index];
    }


    return randomCard;
 }

answered Jun 08 '14 at 22:51

Joe Million

147
9

You should use arc4random_uniform([self.cards count]) to avoid a modulo bias – Paulw11 Jun 08 '14 at 23:20

Trying to generate random numbers on iphone, get same number

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