c - Assign to 2D array a 2D array in a struct -

i have function tries loop through 2d array in struct:

typedef struct node {     int grid[3][3]; } node;   void somefunction(node *node) {      int grid[3][3] = node->grid;      //loop through } 

when try compile

mp.c:42: error: invalid initializer

you cannot assign arrays in c. not allowed. when wrote:

int grid[3][3] = node->grid; 

you attempting initialize local array, grid, passed in node. if permitted (which isn't), you'd not need loop afterwards.

you can assign structures, though, if contain arrays, if local structure node, have written:

node local = *node; 

you not need loop through arrays afterwards initialize local.

you can loop through arrays, doing copy 1 element @ time:

for (int = 0; < 3; i++)     (int j = 0; j < 3; j++)         grid[i][j] = node->grid[i][j]; 

you can use memmove() or memcpy():

int grid[3][3];  assert(sizeof(grid) == sizeof(node->grid)); memcpy(grid, node->grid, sizeof(grid)); 

---

at 1 time, answer suggested:

change line:

int grid[3][3] = node->grid; 

to:

int **grid = node->grid; 

i noted not work - , legitimately challenged explain why. requires space , formatting.

first of all, compiler notes:

warning: initialization incompatible pointer type 

that saying 'you playing fire'.

let's suppose ignore warning. local grid points @ top-left corner of array (if see arrays growing down , across left-to-right). value stored there plain number, not initialized pointer, when compiler evaluates grid[0], forced assume produce pointer. if node->grid[0][0] contains zero, segmentation fault , core dump dereferencing null pointer (on assumption pointers , int same size, true on 32-bit systems), or other undefined behaviour. if node->grid[0][0] contains value, behaviour still undefined, not quite predictable.