Using pointers to iterate through multidimensional array

For example:

constexpr size_t rowCnt = 3, colCnt = 4;

int ia[rowCnt][colCnt] = { // three elements; each element is an array of size 4
     {0, 1, 2, 3}, // initializers for the row indexed by 0
     {4, 5, 6, 7}, // initializers for the row indexed by 1
     {8, 9, 10, 11} // initializers for the row indexed by 2
    };

Not using a type alias for the type of the loop control variables:

// p points to the first array in ia
for (int (*p)[colCnt] = ia; p != ia + rowCnt; ++p) {
    // q points to the first element of an array of four ints; that is, q points to an int
    for (int *q = *p; q != *p + colCnt; ++q)
        cout << *q << " ";
    cout << endl;
}

or easier using auto:

for (auto p = ia; p != ia + rowCnt; ++p) {
    // q points to the first element of an array of four ints; that is, q points to an int
    for (auto q = *p; q != *p + colCnt; ++q)
        cout << *q << " ";
    cout << endl;
}

How about trying like this:-

const int* d = data;
for ( int i = 0; i < width; ++i )
    for ( int j = 0; j < height; ++j )
        for ( int k = 0; k < depth; ++k )
            sum += *d++;

Check this tutorial

Improving texasbruce's answer(couldn't comment sorry) with sizeof trick, assuming array is statically allocated(dimensions are known at compile-time) for(int * iter = &arr[0][0]; iter != &arr[0][0] + sizeof(arr)/sizeof(int); iter++) or iter != (int*)((void*)&arr[0][0] + sizeof(arr)) if you're (void*) fan and hate any compile-time divisions

So you don't have to bother with array dimensions :)

Probably something like this

   for (int **iter = arr; iter != std::end(arr); ++iter) {
        for (int *iter2 = *iter; iter2 != std::end(*arr); ++iter2) {
        // code
        }
    }

Assuming you are simply talking about statically declared multi-dimensional arrays:

const int ROWS = 10;
const int COLS = 20;
const int DEPTH = 30;
int array[ROWS][COLS][DEPTH]; // statically allocated array
int i = 0;
for (int row = 0; row < ROWS; ++row)
{
    for (int col = 0; col < COLS; ++col)
    {
        for (int depth = 0; depth < DEPTH; ++depth)
        {
            *(*(*(array + row) + col) + depth) = i++; // do whatever with it
            // is equivalent to array[row][col][depth] = i++;
        }
    }
} 

If you need more levels, you just keep adding levels of pointer indirection.

Alternatively:

const int ROWS = 5;
const int COLS = 6;
const int DEPTH = 3;
int array[ROWS][COLS][DEPTH]; // statically allocated array
int* p = &array[0][0][0];
int c = 0;
for (int i = 0; i < ROWS * COLS * DEPTH; ++i, p++)
{
    *p = c++;
}

Since a statically declared array is going to be contiguous in memory, with the first element (array[0][0][0]) starting at the base address (&array), this works.

Declaring a multi-dimensional array dynamically is going to be a pointer to an array of pointers to (etc) to pointers to an array of object_type. You can simplify that by using std::vector or std::array (if you know the size at compile time).

Not that these use pointers to iterate (at least not directly), but

Vector/Array

std::vector<std::vector<std::vector<int> > > array;
// or
//std::array<std::array<std::array<int, DEPTH>, COLS>, ROWS> array; // with some slight modifications
// fill in the vectors/arrays however you want

std::for_each(array.begin(), array.end(), [](const std::vector<std::vector<int> >& v)
{
    std::for_each(v.begin(), v.end(), [](const std::vector<int>& a)
    {
        std::for_each(a.begin(), a.end(), [](int i)
        {
            std::cout << i << endl;
        });
    });
});