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copied!<p>Based on a <a href="https://stackoverflow.com/questions/2472944/good-c-array-class-for-dealing-with-large-arrays-of-data-in-a-fast-and-memory">previous question</a>, the approach that I took for handling large arrays that could grow and shrink with reasonable efficiency was to write a container similar to a deque that broke the array down into multiple pages of smaller arrays. So for example, say we have an array of n elements, we select a page size p, and create 1 + n/p arrays (pages) of p elements. When we want to re-allocate and grow, we simply leave the existing pages where they are, and allocate the new pages. When we want to shrink, we free the totally empty pages. </p> <p>The downside is the array access is slightly slower, in that given and index i, you need the page = i / p, and the offset into the page i % p, to get the element. I find this is still very fast however and provides a good solution. Theoretically, std::deque should do something very similar, but for the cases I tried with large arrays it was very slow. See comments and notes on the linked question for more details.</p> <p>There is also a memory inefficiency in that given n elements, we are always holding p - n % p elements in reserve. i.e. we only ever allocate or deallocate complete pages. This was the best solution I could come up with in the context of large arrays with the requirement for re-sizing and fast access, while I don't doubt there are better solutions I'd love to see them.</p>

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