How to create linked list of arrays in c

Question

I want to create a linked list that contains variable-length array-like int A[n][n].

I tried to do it like this, but I'm getting the error Incomplete type is not allowed.

struct Node {
 int A[n][n];
 struct Node* next;
};

Is there any way to do this in c?

For variable length arrays you're gonna need to use a pointer and allocate them dynamically via some constructor function for your struct. — altermetax, May 08 '21 at 18:56

altermetax · Answer 1 · 2021-05-10T10:47:23.867

You'll need to use an int ** allocated on the heap in order to have a variable length. To do that, you need a constructor and a destructor. I also added the ability to specify the next node in the constructor.

struct Node{
    size_t size;
    int **A;
    struct Node* next;
};

void construct_node(struct Node *node, size_t n, struct Node *next_node) {
    node->size = n;
    node->A = malloc(n * sizeof(int *));
    for (size_t i = 0; i < n; i++) {
        node->A[i] = malloc(n * sizeof(int));
    }
    node->next = next_node;
}

void destruct_node(struct Node *node) {
    for (size_t i = 0; i < node->size; i++) {
        free(node->A[i]);
    }
    free(node->A);
    // You probably also want to call destruct_node on the next node to free the entire list:
    // if (node->next) destruct_node(node->next);
}

After doing this, the following code will be required for creating your node:

int size = 10;
struct Node your_node;
construct_node(&your_node, size, NULL);

// Do your stuff with the node

destruct_node(&your_node);

How to create linked list of arrays in c

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