std::map::empty

 

C++

Linguaggio

Concetti

Libreria di Utilità

Stringhe

Contenitori

Algoritmi

Iteratori

Libreria matematca

Input/output

Localizzazione

Espressioni regolari(C++11)

Operazioni atomicche(C++11)

Multithreading(C++11)

 

Contenitori libreria

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

Membri funzioni Original: Member functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

map::map

map::~map

map::operator=

map::get_allocator

Elemento accesso Original: Element access The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

map::at

map::operator[]

Iteratori Original: Iterators The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

map::begin map::cbegin (C++11)

map::end map::cend (C++11)

map::rbegin map::crbegin (C++11)

map::rend map::crend (C++11)

Capacità Original: Capacity The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

map::empty

map::size

map::max_size

Modificatori Original: Modifiers The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

map::clear

map::insert

map::emplace (C++11)

map::emplace_hint (C++11)

map::erase

map::swap

Lookup Original: Lookup The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

map::count

map::find

map::equal_range

map::lower_bound

map::upper_bound

Osservatori Original: Observers The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

map::key_comp

map::value_comp

 

bool empty()const;

Controlla se il contenitore non ha elementi, vale a dire se begin()== end().

Original:

Checks if the container has no elements, i.e. whether begin()== end().

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Parametri

(Nessuno)

Original:

(none)

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Valore di ritorno

true se il contenitore è vuoto, false altrimenti

Original:

true if the container is empty, false otherwise

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Eccezioni

noexcept specification:  

noexcept

  (dal C++11)

Complessità

Constant

Original:

Constant

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Esempio

Il codice seguente utilizza empty per controllare se un std::map<int> contiene elementi:

Original:

The following code uses empty to check if a std::map<int> contains any elements:

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#include <map>#include <iostream>   int main(){std::map<int> numbers;std::cout<<"Initially, numbers.empty(): "<< numbers.empty()<<'\n';   numbers.push_back(42); numbers.push_back(13317);std::cout<<"After adding elements, numbers.empty(): "<< numbers.empty()<<'\n';}

Output:

Initially, numbers.empty(): 1 After adding elements, numbers.empty(): 0

See also

size	restituisce il numero di elementi Original: returns the number of elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico)