std::multimap<Key,T,Compare,Allocator>:: empty
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(C++17)
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| Sequence | ||||
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(C++11)
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(C++26)
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(C++26)
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(C++11)
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| Associative | ||||
| Unordered associative | ||||
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(C++11)
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(C++11)
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(C++11)
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(C++11)
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| Adaptors | ||||
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(C++23)
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(C++23)
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(C++23)
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(C++23)
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| Views | ||||
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(C++20)
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(C++23)
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| Tables | ||||
| Iterator invalidation | ||||
| Member function table | ||||
| Non-member function table |
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| Non-member functions | |||||||||||||||||||||||||||
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| Deduction guides (C++17) | |||||||||||||||||||||||||||
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bool
empty
(
)
const
;
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(noexcept depuis C++11)
(constexpr depuis C++26) |
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Vérifie si le conteneur ne contient aucun élément.
Table des matières |
Valeur de retour
true si le conteneur est vide, false sinon.
Complexité
Constante.
Exemple
Le code suivant utilise
empty
pour vérifier si un
std::
multimap
<
int
,
int
>
contient des éléments :
#include <iostream> #include <map> #include <utility> int main() { std::multimap<int,int> numbers; std::cout << std::boolalpha; std::cout << "Initially, numbers.empty(): " << numbers.empty() << '\n'; numbers.emplace(42, 13); numbers.insert(std::make_pair(13317, 123)); std::cout << "After adding elements, numbers.empty(): " << numbers.empty() << '\n'; }
Sortie :
Initially, numbers.empty(): true After adding elements, numbers.empty(): false
Voir aussi
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retourne le nombre d'éléments
(fonction membre publique) |
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(C++17)
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vérifie si le conteneur est vide
(fonction template) |