void clear() noexcept; | (since C++11) |
Erases all elements from the container.
Invalidates any references, pointers, or iterators referring to contained elements. Any past-the-end iterator remains valid.
(none).
(none).
Linear in the size of the container, i.e., the number of elements.
#include <algorithm> #include <iostream> #include <forward_list> int main() { std::forward_list<int> container{1, 2, 3}; auto print = [](const int& n) { std::cout << " " << n; }; std::cout << "Before clear:"; std::for_each(container.begin(), container.end(), print); std::cout << '\n'; std::cout << "Clear\n"; container.clear(); std::cout << "After clear:"; std::for_each(container.begin(), container.end(), print); std::cout << '\n'; }
Output:
Before clear: 1 2 3 Clear After clear:
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
LWG 2231 | C++11 | complexity guarantee was mistakenly omitted in C++11 | complexity reaffirmed as linear |
(C++11) | erases an element after an element (public member function) |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/w/cpp/container/forward_list/clear