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

From cppreference.com
< cpp‎ | container‎ | map

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

operator[] | access or insert specified element (public member function)

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