I'm confused about your reference to C. C has multidimensional arrays, and all the elements are laid out contiguously in memory. No index calculations are needed, it's all done by the array indexing operation.

If you have this code:

    int a[10][10];

then:

    &a[x][y] == ((char *)a + x * sizeof(a[0]) + y * sizeof(a[0][0]))

where sizeof(a[0]) is == sizeof(int) * 10.

quick edit: added a (char *) cast so the arithmetic doesn't multiply by sizeof(int) again