Existence map in C++

Question

I want something like an std::map, but I only want to see if the item exists or not, I don't actually need a key AND a value. What should I use?

Answer 1

Looks like you need a std::set.

Answer 2

If you want the same type of behavior as std::map, then you want std::set.

If you are mixing insert/delete and query operations, then std::set is probably the best choice. However, if you can populate the set first and then follow it with the queries, it might be worth looking at using std::vector, sorting it, and then using a binary search to check for existence in the vector.