Przejdź do głównej zawartości

std::map at() method

// Non const version
T& at( const Key& key );

// Const version
const T& at( const Key& key ) const;

Returns a reference

to the mapped value of the element with key equivalent to key. If no such element exists, an exception of 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

Throws std::out_of_range if the container doesn't have the key specified.

Complexity

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

Example

Main.cpp
#include <iostream>
#include <map>

auto main() -> int {
std::map<std::string, int> playersScores = {
{ "player1", 50 },
{ "super_coder", 100 },
{ "andrew111", 41 }
};

std::cout << "player1 gained " << playersScores.at("player1") << " points.\n";

// Ooops! Incorrect key!
std::cout << "super_cader gained " << playersScores.at("super_cader") << " points.\n";
}
Possible output
player1 zdobył 50 punktów.
terminate called after throwing an instance of 'std::out_of_range'
what(): map::at
This article originates from this CppReference page. It was likely altered for improvements or editors' preference. Click "Edit this page" to see all changes made to this document.
Hover to see the original license.

std::map at() method

// Non const version
T& at( const Key& key );

// Const version
const T& at( const Key& key ) const;

Returns a reference

to the mapped value of the element with key equivalent to key. If no such element exists, an exception of 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

Throws std::out_of_range if the container doesn't have the key specified.

Complexity

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

Example

Main.cpp
#include <iostream>
#include <map>

auto main() -> int {
std::map<std::string, int> playersScores = {
{ "player1", 50 },
{ "super_coder", 100 },
{ "andrew111", 41 }
};

std::cout << "player1 gained " << playersScores.at("player1") << " points.\n";

// Ooops! Incorrect key!
std::cout << "super_cader gained " << playersScores.at("super_cader") << " points.\n";
}
Possible output
player1 zdobył 50 punktów.
terminate called after throwing an instance of 'std::out_of_range'
what(): map::at
This article originates from this CppReference page. It was likely altered for improvements or editors' preference. Click "Edit this page" to see all changes made to this document.
Hover to see the original license.