Compilare: user.c: In function ‘prod’: user.c:11:2: warning: return from incompatible pointer type [enabled by default] return res; ^ user.c:11:2: warning: function returns address of local variable [-Wreturn-local-addr] user.c: In function ‘put’: user.c:17:3: warning: return from incompatible pointer type [enabled by default] return res; ^ user.c:17:3: warning: function returns address of local variable [-Wreturn-local-addr] user.c:19:2: warning: passing argument 1 of ‘prod’ from incompatible pointer type [enabled by default] int** res = prod(put(n, p/2), put(n, p/2)); ^ user.c:4:7: note: expected ‘int (*)[2]’ but argument is of type ‘int **’ int** prod(int a[2][2], int b[2][2]) { ^ user.c:19:2: warning: passing argument 2 of ‘prod’ from incompatible pointer type [enabled by default] int** res = prod(put(n, p/2), put(n, p/2)); ^ user.c:4:7: note: expected ‘int (*)[2]’ but argument is of type ‘int **’ int** prod(int a[2][2], int b[2][2]) { ^ user.c:21:3: warning: passing argument 1 of ‘prod’ from incompatible pointer type [enabled by default] res = prod(res, n); ^ user.c:4:7: note: expected ‘int (*)[2]’ but argument is of type ‘int **’ int** prod(int a[2][2], int b[2][2]) { ^ user.c: In function ‘main’: user.c:29:8: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d\n", &k); ^