如何在Objective-C中添加和更新二维数组的对象？

Question

I want to make a two dimensional array in objective-c and initialize all the indexes as zero. whenever my data (2D Coordinate) matches with any row/column then I want to upgrade the respective index by value one. So that later on I can scan for my highly probable coordinate on the basis of maximum number of index at any point. For eg: If my algorithm generates coordinate (0,1), then the index at first row and second column must increase by one. Thanks a lot.

Answer 1

Here is how you create your array.

NSMutableArray *array = [[NSMutableArray alloc] init];

[array addObject:[NSMutableArray arrayWithObjects:@"0",@"0",nil]];
[array addObject:[NSMutableArray arrayWithObjects:@"0",@"0",nil]];
NSLog(@"%@",array);

Update value

Say you want to update index(0,1) with value 3 , you do

[[array objectAtIndex:0] replaceObjectAtIndex:1 withObject:@"3"];
NSLog(@"%@",array);

Update index(1,1) with value 4 do

[[array objectAtIndex:1] replaceObjectAtIndex:1 withObject:@"4"];
NSLog(@"%@",array);

Hope it helps.

Cheers.

Answer 2

如果需要，可以使用数字并使用简单的方法来编写数组：

NSMutableArray * array2d = @[@[@0,@0], @[@0,@1]];

Answer 3

Just a suggestion:

Objective-C is a super set of C. So you can make use of the C array concept also.

int array2D[5][5] = {0};//The compiler will automatically intialize all indces to 0.

or use

memset(&a[0][0], 0, sizeof(int) * 5 * 5);

then use the simple C assignment like as follows,

array2D[0][1] = 3;

which is much faster and simple.

Sample Code:

#include<stdio.h>
#include<string.h>

int main(int argc, char * argv[])
{
  int a[5][5];

  memset(&a[0][0], 0, sizeof(int) * 5 * 5);

  for(int  i = 0;  i < 5; i++)
  {
    for(int j = 0; j < 5; j++)
    {
      printf("%d ", a[i][j]);
    }

    printf("\n");
  }

  return 0;
}