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

From cppreference.com

 
 
 
 
void clear() noexcept;
(since C++11)

Erases all elements from the container.

Invalidates any references, pointers, and 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

#include <iostream>
#include <string_view>
#include <forward_list>
 
void print_info(std::string_view rem, const std::forward_list<int>& v)
{
    std::cout << rem << "{ ";
    for (const auto& value : v)
        std::cout << value << ' ';
    std::cout << "}\n";
}
 
int main()
{
    std::forward_list<int> container{1, 2, 3};
    print_info("Before clear: ", container);
    container.clear();
    print_info("After clear: ", container);
}

Output:

Before clear: { 1 2 3 }
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

erases an element after an element
(public member function)