std::flat_set

The flat set is a container adaptor that gives the functionality of an associative container that stores a sorted set of unique objects of type Key. Sorting is done using the key comparison function Compare.

# Declarations

template<
class Key,
class Compare = std::less<Key>,
class KeyContainer = std::vector<Key>
> class flat_set;

(since C++23)

# Notes

The member types iterator and const_iterator may be aliases to the same type. This means defining a pair of function overloads using the two types as parameter types may violate the One Definition Rule. Since iterator is convertible to const_iterator, a single function with a const_iterator as parameter type will work instead.

Some advantages of flat set over other standard container adaptors are:

Some disadvantages of flat set are:

# See also

• flat_multiset
• set
• unordered_set