std::vector::empty

 

C++

Язык

Понятия (концепции)

Утилиты

Строки

Контейнеры

Алгоритмы

Итераторы

Работа с числами

Ввод / вывод

Локализация

Регулярные выражения (C++11)

Атомарные примитивы (C++11)

Потоки (C++11)

 

Контейнеры

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::vector

Член функций 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.

vector::vector

vector::~vector

vector::operator=

vector::assign

vector::get_allocator

Элемент доступа 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.

vector::at

vector::operator[]

vector::front

vector::back

vector::data (C++11)

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

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

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

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

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

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

vector::empty

vector::size

vector::max_size

vector::reserve

vector::capacity

vector::shrink_to_fit (C++11)

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

vector::clear

vector::insert

vector::emplace (C++11)

vector::erase

vector::push_back

vector::emplace_back (C++11)

vector::pop_back

vector::resize

vector::swap

 

bool empty() const;

Проверки, если контейнер не имеет элементов, т.е. является ли begin() == end().

Original:

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

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Параметры

(Нет)

Original:

(none)

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Возвращаемое значение

true если контейнер пуст, false иначе

Original:

true if the container is empty, false otherwise

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Исключения

noexcept-спецификация:  

noexcept

  (начиная с C++11)

Сложность

Constant

Original:

Constant

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Пример

Следующий код использует empty, чтобы проверить, std::vector<int> содержит никаких элементов

Original:

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

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#include <vector>
#include <iostream>
 
int main()
{
    std::vector<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';
}

Вывод:

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

See also

size	возвращает количество элементов 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. (public функция-член)