std::deque::empty

 

C++

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std::deque

Member functions

deque::deque

deque::~deque

deque::operator=

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Element access

deque::front

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Iterators

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

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

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Capacity

deque::empty

deque::size

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deque::shrink_to_fit

Modifiers

deque::clear

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deque::pop_back

deque::resize

deque::swap

 

bool empty() const;

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

Parameters

(none)

Return value

true if the container is empty, false otherwise

Exceptions

noexcept specification:  

noexcept

  (since C++11)

Complexity

Constant

Example

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

#include <deque>
#include <iostream>
 
int main()
{
    std::deque<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	returns the number of elements (public member function)