Array Shuffle?

thisismyurl · June 2009

Hi all, sorry if this is a painfully simple question but ...

in PHP we have a command called shuffle() which randomizes the order of an array (ie shuffle($myArray)).

Is there something similar on the iPhone?

--
Christopher Ross (complete iPhone noob)
Christopher Ross :: Technology Evangelism, Web Marketing and Internet Consulting

gaoning87 · June 2009

thisismyurl;97133 said:
Hi all, sorry if this is a painfully simple question but ...

in PHP we have a command called shuffle() which randomizes the order of an array (ie shuffle($myArray)).

Is there something similar on the iPhone?

--
Christopher Ross (complete iPhone noob)
Christopher Ross :: Technology Evangelism, Web Marketing and Internet Consulting

nope,there isn't offcal function for shuffling array.Tell you some:
1.random a number or something by including math.h and another header(I forgot,you can google)
2.call a for loop,push every number you randomed into your array
what do you think about?
send me a feedback

Avocado · June 2009

Another approach, using an NSMutableArray:

#import "time.h"

...

srand( time(NULL) );

int randomIndex;

for( int index = 0; index < numItems; index++ )
{
randomIndex= rand() % numItems + 1;

[theArray exchangeObjectAtIndex:index withObjectAtIndex:randomIndex];
}

Hopefully that works.

kalx · June 2009

Avocado;97264 said:
Another approach, using an NSMutableArray:

#import "time.h"

...

srand( time(NULL) );

int randomIndex;

for( int index = 0; index < numItems; index++ )
{
randomIndex= rand() % numItems + 1;

[theArray exchangeObjectAtIndex:index withObjectAtIndex:randomIndex];
}

Hopefully that works.

That should be a good solution for the OP, except I don't think you want to add 1 to the random index.

randomIndex= rand() % numItems + 1;

If your numItems is 5, you want the randomIndex to be a value from 0 through 4, but by adding 1 you're effectively making it 1 through 5 instead.

- kalx

Avocado · June 2009

kalx;97268 said:
That should be a good solution for the OP, except I don't think you want to add 1 to the random index.

randomIndex= rand() % numItems + 1;

If your numItems is 5, you want the randomIndex to be a value from 0 through 4, but by adding 1 you're effectively making it 1 through 5 instead.

- kalx

Absolutely right, nice catch.

thisismyurl · June 2009

@all, thanks for the reply and support.

I'm a complete noob at this and don't want to trouble you guys with every question, but I really really appreciate this piece of code! Thank you.

Chris.

gaoning87 · June 2009

thisismyurl;97300 said:
@all, thanks for the reply and support.

I'm a complete noob at this and don't want to trouble you guys with every question, but I really really appreciate this piece of code! Thank you.

Chris.

um,you can question me every time.
my mail:gaoning87@163.com

MikesTooLz · June 2009

I just used this in my bingo app to shuffle what the game squares say.
Thanks

sherwood87 · October 2011

//Use a trick to "sort" the array into random order.
//this trick involves using a sort function "randomize" that puts
//the items in random order.
[randomArray sortUsingFunction: randomize context:NULL];

Oliver Drobnik · November 2011

Shuffling an NSArray | Cocoanetics

Howdy, Stranger!

Forums

Array Shuffle?

Replies