std::map<Key,T,Compare,Allocator>::at

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T& at( const Key& key );
(1)
const T& at( const Key& key ) const;
(2)

Returns a reference to the mapped value of the element with key equivalent to key. If no such element exists, an exception of type std::out_of_range is thrown.

Parameters

key - the key of the element to find

Return value

Reference to the mapped value of the requested element.

Exceptions

std::out_of_range if the container does not have an element with the specified key.

Complexity

Logarithmic in the size of the container.

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 464 C++98 map did not have this member function added
LWG 703 C++98 the complexity requirement was missing added
LWG 2007 C++98 the return value referred to the requested element refers to its mapped value

See also

access or insert specified element
(public member function)