在二维数组上创建指针的动态数组

Question

I'm kind of stuck since i'm trying to do what is in the title. instinctively i would do this :

size = 10 //(for example)
int** pieces[10][10];
pieces* = (int*)malloc(sizeof(int*)*size);

But it doesn't even compile.

Do you have any idea ? Thank you !

Answer 1

In order not to mix up the syntax with "array of pointers", you need to do this:

int (*pieces) [10][10]; // pointer to int [10][10]

And then to allow convenient access with syntax pieces[i][j] rather than (*pieces)[i][j] , drop the outer-most dimension:

int (*pieces) [10]; // pointer to int[10], the type of the first element of a int[10][10].

Allocate with

pieces = malloc( sizeof(int[10][10]) );
...
free(pieces);

Details here: Correctly allocating multi-dimensional arrays

Answer 2

you are trying to make a pointer to a pointer to an array of 2d of ints. you need to delete the bracktes ([10][10]) you should allocate an array of pointers for the rows pieces = (int**)malloc(sizeof(int*)*size); and then allocate for each column with a loop like this:

int i;

for (i = 0; i < size; i++)
    pieces[i] = (int*)malloc(sizeof(int));

afterwards you will need to free all the column allocations and then first row allocation of pieces.