Random with selected number in xcode

Question

I have numbers in integer that is 0, 17, 23, 44, 57, 60, 66, 83, 89, 91, 100, but i want to random 6 number from that number, how to do that? I can show only for one random number from 0-100 but i dont know how to show 6 number from selected number. Please teach.

those integer value inserted into array or not? – Nimit Parekh Aug 24 '12 at 12:36 — Nimit Parekh, Aug 24 '12 at 12:36

score 2 · Accepted Answer · answered Aug 24 '12 at 12:39

If you would like to pick six numbers without repetitions from the array, shuffle the array using Knuth-Fisher–Yates shuffle, and take the first six numbers:

int data[] = {0, 17, 23, 44, 57, 60, 66, 83, 89, 91, 100};
// Knuth-Fisher-Yates
for (int i = 10 ; i > 0 ; i--) {
    int n = rand() % (i+1);
    int tmp = data[i];
    data[i] = data[n];
    data[n] = tmp;
}

The first six elements of the data array contain a random selection from the original 11-element array.

+1 : indeed he needs a shuffle behavior not a random one in this particular case ! — Seb T., Aug 24 '12 at 12:50

score 1 · Answer 2 · answered Aug 24 '12 at 12:34

1

Put the numbers in an array. Use a random number generator to get a random number between 0 and 1 less than the length of the array, and then get the number at that index.

That's just one way of doing it.

answered Aug 24 '12 at 12:34

Abizern

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score 1 · Answer 3 · answered Aug 24 '12 at 12:37

1

For fetching the random number into array for that following code may be useful to you

[array objectAtIndex: (random() % [array count])]

Here is the example

NSUInteger firstObject = 0;

for (int i = 0; i<[myNSMutableArray count];i++) {
    NSUInteger randomIndex = random() % [myNSMutableArray count];
    [myNSMutableArray exchangeObjectAtIndex:firstObject withObjectAtIndex:randomIndex];
    firstObject +=1;

}

answered Aug 24 '12 at 12:37

Nimit Parekh

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Your implementation contains a very common [implementation error of picking a random element from the entire range](http://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle#Implementation_errors). The selection is biased, as explained in the wiki article. – Sergey Kalinichenko Aug 24 '12 at 12:48
Thanks for informing me.+1 for it – Nimit Parekh Aug 24 '12 at 12:50

score 0 · Answer 4 · edited May 23 '17 at 12:27

0

See this post: Generating random numbers in Objective-C

There are lots of ways to do this. This particular method has a very good response. To get 6 random numbers simply run the function 6 times.

edited May 23 '17 at 12:27

Community

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answered Aug 24 '12 at 12:36

ddoor

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Random with selected number in xcode

4 Answers4