std::map::operator[]

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C++ Standard Library
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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::begin map::cbegin (C++11) map::end map::cend (C++11) map::rbegin map::crbegin (C++11) map::rend map::crend (C++11) Capacity map::empty map::size map::max_size Modifiers map::clear map::insert map::emplace (C++11) map::emplace_hint (C++11) 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

T& operator[]( const Key& key );	(1)
T& operator[]( Key&& key );	(2)	(since C++11)

Inserts a new element to the container using key as the key and default constructed mapped value and returns a reference to the newly constructed mapped value. If an element with key key already exists, no insertion is performed and a reference to its mapped value is returned.

1) Essentially performs (insert(std::make_pair(key, T())).first)->second.

2) Essentially performs (insert(std::make_pair(std::move(key), T())).first)->second.

No iterators or references are invalidated.

Contents 1 Parameters 2 Return value 3 Complexity 4 See also

[edit] Parameters

key

-

the key of the element to find

[edit] Return value

reference to the mapped value of the new element if no element with key key existed. Otherwise a reference to the mapped value of the existing element is returned.

[edit] Complexity

This section is incomplete

[edit] See also

at (C++11)	access specified element with bounds checking (public member function)