// tag
#containers
2 posts tagged #containers.
std::inplace_vector is a vector that never touches the heap
C++26 adds std::inplace_vector<T, N>, a sequence container with a fixed compile-time capacity whose storage lives inside the object. It gives you a vector's dynamic size and push_back with zero heap allocation, which is exactly what embedded, real-time, and hot-path code has been hand-rolling for decades. GCC 16.1 ships it now.
std::flat_map is just two vectors
C++23's std::flat_map is an adaptor over a sorted vector of keys and a parallel vector of values. That buys cache-friendly lookups and near-zero memory overhead, and costs O(n) insertion and aggressive iterator invalidation. It replaces std::map, not std::unordered_map, and knowing which vector trick it is tells you exactly when to reach for it.