std::set (3) - Linux Manuals
std::set: std::set
NAME
Synopsis
Defined in header <set>
template<
class Key,
class Compare = std::less<Key>, (1)
class Allocator = std::allocator<Key>
> class set;
namespace pmr {
template <class Key, class Compare = std::less<Key>> (2) (since C++17)
using set = std::set<Key, Compare, std::pmr::polymorphic_allocator<Key>>;
}
std::set is an associative container that contains a sorted set of unique objects of type Key. Sorting is done using the key comparison function Compare. Search, removal, and insertion operations have logarithmic complexity. Sets are usually implemented as red-black_trees.
Everywhere the standard library uses the Compare requirements, uniqueness is determined by using the equivalence relation. In imprecise terms, two objects a and b are considered equivalent if neither compares less than the other: !comp(a, b) && !comp(b, a).
std::set meets the requirements of Container, AllocatorAwareContainer, AssociativeContainer and ReversibleContainer.
Member types
Member type Definition
key_type Key
value_type Key
size_type Unsigned integer type (usually std::size_t)
difference_type Signed integer type (usually std::ptrdiff_t)
key_compare Compare
value_compare Compare
allocator_type Allocator
reference Allocator::reference (until C++11)
const_reference Allocator::const_reference (until C++11)
pointer Allocator::pointer (until C++11)
const_pointer Allocator::const_pointer (until C++11)
iterator Constant LegacyBidirectionalIterator
const_iterator Constant LegacyBidirectionalIterator
reverse_iterator std::reverse_iterator<iterator>
const_reverse_iterator std::reverse_iterator<const_iterator>
node_type(since C++17) a specialization of node_handle representing a container node
insert_return_type(since C++17) bool inserted;
Member functions
constructor (public member function)
destructor (public member function)
operator= (public member function)
get_allocator (public member function)
Iterators
begin returns an iterator to the beginning
cbegin (public member function)
end_ returns an iterator to the end
cend (public member function)
rbegin returns a reverse iterator to the beginning
crbegin (public member function)
rend returns a reverse iterator to the end
crend (public member function)
Capacity
empty (public member function)
size (public member function)
max_size (public member function)
Modifiers
clear (public member function)
insert (since C++17)
emplace constructs element in-place
(C++11)
emplace_hint constructs elements in-place using a hint
(C++11)
erase (public member function)
swap (public member function)
extract extracts nodes from the container
(C++17)
merge splices nodes from another container
(C++17)
Lookup
count (public member function)
find (public member function)
contains checks if the container contains element with specific key
(C++20)
equal_range (public member function)
lower_bound (public member function)
upper_bound (public member function)
Observers
key_comp (public member function)
value_comp (public member function)
Non-member functions
operator==
operator!= lexicographically compares the values in the set
operator< (function template)
operator<=
operator>
operator>=
std::swap(std::set) (function template)
erase_if(std::set) Erases all elements satisfying specific criteria
(C++20)
Deduction_guides(since C++17)
Notes
The member types iterator and const_iterator may be aliases to the same type. Since iterator is convertible to const_iterator, const_iterator should be used in function parameter lists to avoid violations of the One Definition Rule.
Defect Reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR Applied to Behavior as published Correct behavior
LWG_103 C++98 iterator allows modification of keys iterator made constant