std::map::insert

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Technical Specifications

 

Containers library

array (C++11)

vector

deque

forward_list (C++11)

list

set

multiset

map

multimap

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

stack

queue

priority_queue

 

std::map

Member functions

map::map

map::~map

map::operator=

map::get_allocator

Element access

map::at

map::operator[]

Iterators

map::beginmap::cbegin (C++11)

map::endmap::cend (C++11)

map::rbeginmap::crbegin (C++11)

map::rendmap::crend (C++11)

Capacity

map::empty

map::size

map::max_size

Modifiers

map::clear

map::insert

map::insert_or_assign (C++17)

map::emplace (C++11)

map::emplace_hint (C++11)

map::try_emplace (C++17)

map::erase

map::swap

Lookup

map::count

map::find

map::equal_range

map::lower_bound

map::upper_bound

Observers

map::key_comp

map::value_comp

 

std::pair<iterator,bool> insert( const value_type& value );	(1)
template< class P > std::pair<iterator,bool> insert( P&& value );	(2)	(since C++11)
std::pair<iterator,bool> insert( value_type&& value );	(2)	(since C++17)
	(3)
iterator insert( iterator hint, const value_type& value );			(until C++11)
iterator insert( const_iterator hint, const value_type& value );			(since C++11)
template< class P > iterator insert( const_iterator hint, P&& value );		(4)	(since C++17)
iterator insert( const_iterator hint, value_type&& value );		(4)	(since C++11)
template< class InputIt > void insert( InputIt first, InputIt last );		(5)
void insert( std::initializer_list<value_type> ilist );		(6)	(since C++11)

Inserts element(s) into the container, if the container doesn't already contain an element with an equivalent key.

1-2) Inserts value. The overload (2) is equivalent to emplace(std::forward<P>(value)) and only participates in overload resolution if std::is_constructible<value_type, P&&>::value == true.

3-4) Inserts value in the position as close as possible, just prior(since C++11), to hint. The overload (4) is equivalent to emplace_hint(hint, std::forward<P>(value)) and only participates in overload resolution if std::is_constructible<value_type, P&&>::value == true.

5) Inserts elements from range [first, last).

6) Inserts elements from initializer list ilist.

No iterators or references are invalidated.

Parameters

hint	-	iterator, used as a suggestion as to where to start the search (until C++11) iterator to the position before which the new element will be inserted (since C++11)
value	-	element value to insert
first, last	-	range of elements to insert
ilist	-	initializer list to insert the values from
Type requirements
- InputIt must meet the requirements of InputIterator.

Return value

1-2) Returns a pair consisting of an iterator to the inserted element (or to the element that prevented the insertion) and a bool denoting whether the insertion took place.

3-4) Returns an iterator to the inserted element, or to the element that prevented the insertion.

5-6) (none)

Exceptions

1-4) If an exception is thrown by any operation, the insertion has no effect.

Complexity

1-2) Logarithmic in the size of the container, O(log(size())).

3-4) Amortized constant if the insertion happens in the position just after the hint, logarithmic in the size of the container otherwise.	(until C++11)
3-4) Amortized constant if the insertion happens in the position just before the hint, logarithmic in the size of the container otherwise.	(since C++11)

5-6) O(N*log(size() + N)), where N is the number of elements to insert.

Notes

The hinted insert (3,4) does not return a boolean in order to be signature-compatible with positional insert on sequential containers, such as std::vector::insert. This makes it possible to create generic inserters such as std::inserter. One way to check success of a hinted insert is to compare size() before and after.

See also

emplace (C++11)	constructs element in-place (public member function)
emplace_hint (C++11)	constructs elements in-place using a hint (public member function)