What is the difference between using the std::set container and the std::unordered_set container in C++?

The main difference between std::set and std::unordered_set in C++ is in how they store and organize elements:

• std::set is an ordered container that stores elements in sorted order (usually ascending). It is implemented based on a balanced tree (e.g., red-black tree). Search, insertion, and deletion have logarithmic complexity O(log n).

• std::unordered_set is an unordered container that stores elements in a hash table. Elements have no defined order. Search, insertion, and deletion have amortized constant complexity O(1), but in the worst case, O(n).

The choice depends on requirements:

• Use std::set if an ordered set with iteration in sorted order is needed.
• Use std::unordered_set if maximum access speed without order is important.