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         


        

Answer 1

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

Answer 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);

Answer 3

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]];
}