MultiDimensional Array in Objective c

Question

EveryBody..

i want to create one 8*8 dimensional array in objective c..

(
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
)

like that.. And also use as one of the object can moved in it.. Like want to move

MOVE_ARRAY = array([0, 0], [0, 2])

And also check the array's any position like 5*6 or 4*3 any.. So, Can any one help me about how to initialize , and how to use in code ? Thanks.

Do you know to create a multidimensional(2D) array in any other programming language? Also a 64D would redefine physics. I am assuming you need a 2D array. — Praveen S
– Praveen S, Commented Aug 29, 2011 at 7:42
Objective C is backward compatible with C/C++. You can create a simple C array and use it... if you cannot create that, you've a lot of ground to cover before you jump into iPhone development.. — Swapnil Luktuke
– Swapnil Luktuke, Commented Aug 29, 2011 at 7:50
@WTP i didn't told that array is 64D.. i just show you the position of the objects in. — Solid Soft
– Solid Soft, Commented Aug 29, 2011 at 8:33
@Praveen S.. yes i need 2D array and i displaying the positions of the objects.. — Solid Soft
– Solid Soft, Commented Aug 29, 2011 at 8:34

joern · Accepted Answer · 2011-08-29 09:47:00Z

7

In Objective-C:

array = [[NSMutableArray alloc] init];

for (int i = 0; i < 8; i++) {
    NSMutableArray *subArray = [[NSMutableArray alloc] init];
    for (int j = 0; j < 8; j++) {
        [subArray addObject:[NSNumber numberWithInt:0]]; 
    }
    [array addObject:subArray];
    [subArray release];
}

(array is an instance variable, that has to be added to your header file and released in you dealloc method)

To retrieve a value at a certain position you could write a method like this:

- (int)valueAtRow:(int)row andColumn:(int)col {
    NSMutableArray *subArray = [array objectAtIndex:row];
    return [[subArray objectAtIndex:col] intValue];
}

=== UPDATE ===

To remove an object you could do this:

- (void)removeObjectAtRow:(int)row andColumn:(int)col {
    NSMutableArray *subArray = [array objectAtIndex:row];
    [subArray removeObjectAtIndex:col];
}

You have to be careful though, because removing objects will change the structure of the array (e.g. the row where you removed an object will have only 7 items after the removal. So you might want to think about leaving the structure intact and set the values that you want to delete to a value that you normally don't use:

- (void)removeObjectAtRow:(int)row andColumn:(int)col {
    NSMutableArray *subArray = [array objectAtIndex:row];
    [subArray replaceObjectAtIndex:col withObject:[NSNumber numberWithInt:-999]];
}

edited Aug 29, 2011 at 9:47

answered Aug 29, 2011 at 8:12

joern

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4 Comments

Solid Soft Over a year ago

And If i want to remove the any position , So how i could ?

Nekto Over a year ago

With such implementation it's not possible just to write array[i][j]. But question was in that. So -1...

Solid Soft Over a year ago

Hey joerm... I m very thankful to you.. And need one more help. One more query, i m using this array and in running code i need to change index with another index.. How it ?

joern Over a year ago

Hi Jagdish. I'm afraid I do not fully understand what you try to achieve. Do you want to swap two values? Like for example swap the value in row 1, column 2 with the value at row2 and column 1?

Nekto · Accepted Answer · 2011-08-29 07:48:41Z

2

In C:

int **array = (int**)calloc(8, sizeof(int*));
for (int i=0; i<8; i++) array[i] = (int*)calloc(8, sizeof(int));
// use your array
// cleaning:
for (int i=0; i<8; i++) free(array[i]);
free(array);

answered Aug 29, 2011 at 7:48

Nekto

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Comments

Radim Köhler · Accepted Answer · 2013-12-08 07:31:54Z

2

To create a constant 2d array containing integers,simply do something like:

NSArray *array;
array = @[@[@1, @7, @4, @11],@[@2, @6, @9]];

This creates an array

1 7 4 11
2 6 9

edited Dec 8, 2013 at 7:31

Radim Köhler

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answered Dec 8, 2013 at 7:10

tangkk

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