# std::forward_list<T,Allocator>::clear

From cppreference.com
< cpp‎ | container‎ | forward list

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.

### Parameters

(none)

### Return value

(none)

### Complexity

Linear in the size of the container, i.e., the number of elements.

### Example

Run this code

    #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:

### Defect reports

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

### See also

erase_after (C++11) | erases an element after an element (public member function)

Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/container/forward_list/clear&oldid=156306"