Very specific problem, possibly due to my generally poor understanding of multidimensional arrays in C. I've got this code:

```
int io_pipes[NUM_IO_PROC][n][2][2];

for (int i = 0; i < n; ++i) {
    int pipes[NUM_IO_PROC][2][2];
    for (int j = 0; j < NUM_IO_PROC; ++j) pipes[j] = io_pipes[j][i];
}

```

There's some stuff missing, of course (like what happens to the `pipes` variable). Problem is that on line 5 there, I get a compiler error that say "incompatible type in assignment." I'd like it if the compiler gave me more information because as far as I know, `pipes[j]` and `io_pipes[j][i]` are both of type `int[2][2]`.