std::vector<T,Allocator>::empty

 

C++

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std::vector

Member types
Member functions
vector::vector vector::~vector vector::operator= vector::assign vector::assign_range (C++23)   vector::get_allocator Element access vector::operator[] vector::at vector::data vector::front vector::back Iterators vector::beginvector::cbegin (C++11) vector::endvector::cend (C++11) vector::rbeginvector::crbegin (C++11) vector::rendvector::crend (C++11)	Capacity vector::empty vector::size vector::max_size vector::reserve vector::capacity vector::shrink_to_fit (DR*) Modifiers vector::clear vector::erase vector::insert vector::insert_range (C++23) vector::append_range (C++23) vector::emplace (C++11) vector::emplace_back (C++11) vector::push_back vector::pop_back vector::resize vector::swap
Non-member functions
operator==operator<=> (C++20) swap(std::vector) erase(std::vector)erase_if(std::vector) (C++20)(C++20)	operator!=operator<operator>operator<=operator>= (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)
Deduction guides(C++17)

 

bool empty()const;		(noexcept since C++11) (constexpr since C++20)

Checks if the container has no elements.

Return value

true if the container is empty, false otherwise.

Complexity

Constant.

Example

Run this code

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

Output:

Initially, numbers.empty(): true After adding elements, numbers.empty(): false

See also

size	returns the number of elements (public member function)
empty (C++17)	checks whether the container is empty (function template)