std::vector<T,Allocator>::empty
bool empty() const; |
(until C++11) | |
bool empty() const noexcept; |
(since C++11) (until C++20) |
|
[[nodiscard]] constexpr bool empty() const noexcept; |
(since C++20) |
Checks if the container has no elements, i.e. whether begin() == end().
Parameters
(none).
Return value
true if the container is empty, false otherwise.
Complexity
Constant.
Example
#include <vector>
#include <iostream>
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
| returns the number of elements (public member function) |
|
|
(C++17)
|
checks whether the container is empty (function template) |
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