Difference between revisions of "cpp/container/vector/empty"
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Latest revision as of 07:05, 7 November 2021
bool empty() const; |
(noexcept since C++11) (constexpr since C++20) |
|
Checks if the container has no elements, i.e. whether begin() == end().
Contents |
[edit] Parameters
(none)
[edit] Return value
true if the container is empty, false otherwise.
[edit] Complexity
Constant.
[edit] 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
[edit] See also
| returns the number of elements (public member function) | |
| (C++17) |
checks whether the container is empty (function template) |
