Comment by umanwizard

An array of arrays is an extremely inefficient and error-prone way to represent multidimensional arrays.

If I want a 1000x1000 array, representing it physically as a single 1000000-element array requires one allocation, and processing it element-by-element (assuming it's stored in the same order we're iterating over it) is sequential in memory and therefore very efficient.

Representing it as 1000 separate 1000-element arrays requires 1000 allocations, and pointer-chasing every time we move from one row to the next.