class value_compare; std::map::value_compare is a function object that compares objects of type std::map::value_type (key-value pairs) by comparing of the first components of the pairs. Member types Type Definition result_type bool first_argument_type value_type second_argument_type value_type Protected member objects Compare comp the stored comparator (protected member object) Member functions (constructor) constructs a new value_compare object (pro

std::map::value_compare value_comp() const; Returns a function object that compares objects of type std::map::value_type (key-value pairs) by using key_comp to compare the first components of the pairs. Parameters (none). Return value The value comparison function object. Complexity Constant. See also key_comp returns the function that compares keys (public member function)

iterator upper_bound( const Key& key ); (1) const_iterator upper_bound( const Key& key ) const; (1) template< class K > iterator upper_bound( const K& x ); (2) (since C++14) template< class K > const_iterator upper_bound( const K& x ) const; (2) (since C++14) 1) Returns an iterator pointing to the first element that is greater than key. 2) Returns an iterator pointing to the first element that compares greater to the value x. This overlo

template <class... Args> pair<iterator, bool> try_emplace(const key_type& k, Args&&... args); (1) (since C++17) template <class... Args> pair<iterator, bool> try_emplace(key_type&& k, Args&&... args); (2) (since C++17) template <class... Args> iterator try_emplace(const_iterator hint, const key_type& k, Args&&... args); (3) (since C++17) template <class... Args> iterator try_emplace(const_iterator hin

void swap( map& other ); Exchanges the contents of the container with those of other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated. The Pred objects must be Swappable, and they are exchanged using unqualified call to non-member swap. If std::allocator_traits<allocator_type>::propagate_on_container_swap::value is true, then the allocators are exchanged using an unq

size_type size() const; Returns the number of elements in the container, i.e. std::distance(begin(), end()). Parameters (none). Return value The number of elements in the container. Exceptions (none) (until C++11) noexcept specification: noexcept (since C++11) Complexity Constant. Example The following code uses size to display the number of elements in a std::map: #include <map> #include <iostream> int main() { std::map<int,char> nums {{1, '

reverse_iterator rend(); const_reverse_iterator rend() const; const_reverse_iterator crend() const; (since C++11) Returns a reverse iterator to the element following the last element of the reversed container. It corresponds to the element preceding the first element of the non-reversed container. This element acts as a placeholder, attempting to access it results in undefined behavior. Parameters (none). Return value Reverse iterator to the element following the last

reverse_iterator rbegin(); const_reverse_iterator rbegin() const; const_reverse_iterator crbegin() const; (since C++11) Returns a reverse iterator to the first element of the reversed container. It corresponds to the last element of the non-reversed container. Parameters (none). Return value Reverse iterator to the first element. Exceptions (none) (until C++11) noexcept specification: noexcept (since C++11) Complexity Constant. See also rend crend r

T& operator[]( const Key& key ); (1) T& operator[]( Key&& key ); (2) (since C++11) Returns a reference to the value that is mapped to a key equivalent to key, performing an insertion if such key does not already exist. 1) Inserts value_type(key, T()) if the key does not exist. This function is equivalent to return insert(std::make_pair(key, T())).first->second; - key_type must meet the requirements of CopyConstructible. - mapped_type must meet the requi

size_type max_size() const; Returns the maximum number of elements the container is able to hold due to system or library implementation limitations, i.e. std::distance(begin(), end()) for the largest container. Parameters (none). Return value Maximum number of elements. Exceptions (none) (until C++11) noexcept specification: noexcept (since C++11) Complexity Constant. Notes This value is typically equal to std::numeric_limits<size_type>::max(), and reflects the