Three dimensional arrays of integers in C++

Question

I would like to find out safe ways of implementing three dimensional arrays of integers in C++, using pointer arithmetic / dynamic memory allocation, or, alternatively using

Answer 1

It should be noted that, for all intents and purposes, you are dealing with only a 2D array, because the third (and least significant) dimension is known.

Using the STL or Boost are quite good approaches if you don't know beforehand how many entries you will have in each dimension of the array, because they will give you dynamic memory allocation, and I recommend either of these approaches if your data set is to remain largely static, or if it to mostly only receive new entries and not many deletions.

However, if you know something about your dataset beforehand, such as roughly how many items in total will be stored, or if the arrays are to be sparsely populated, you might be better off using some kind of hash/bucket function, and use the XYZ indices as your key. In this case, assuming no more than 8192 (13 bits) entries per dimension, you could get by with a 40-bit (5-byte) key. Or, assuming there are always 4 x Z entries, you would simply use a 26-bit XY key. This is one of the more efficient trade-offs between speed, memory usage, and dynamic allocation.