For example I have an array of 200 integers. What I want to do is convert it to two arrays of 80 integers, removing the 40 integers in between. The goal of course is to use the existing memory block without allocating two new arrays of length 80 integers and copying from the first array, what I want is to cut the initial array from 80 to 120 and treat what is left as two separate arrays.
Move semantics uses a similar low level approach to avoid unnecessary copy of rvalues, so my question is if there is a low level approach to achieve a similar effect but assign the already existing data to multiple objects.
For example assigning pointers to the raw memory addresses of where the cuts are and the new elements begin, forcing them to act as arrays which use the same data, already allocated and filled in by the initial array?
Naturally, I could also delete the initial array and get its address and use that to assign its memory area to a new element, but is it possible to tell C++ on which exact address to allocate a new object? And also, is there a way to guarantee the data of the initial array wont be corrupted in between its deletion and the reallocation of that same memory area to a new object?
Such an approach is absent from any of the books on c++ I’ve read, but I get the feeling there might very well be some low level trickery to achieve the desired result.
Yes, this is possible using placement-new. However, there is no way to guarantee that the content of a memory-location will not be changed between delete and a reallocation. Anyway, placement-new only enables you to construct an object in memory that you already own. So you’d have to allocate a pool of memory and then do your own memory management inside that pool.