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

From cppreference.com
< cpp‎ | container‎ | list
 
 
 
 
void clear();
(until C++11)
void clear() noexcept;
(since C++11)

Erases all elements from the container. After this call, size() returns zero.

Invalidates any references, pointers, or iterators referring to contained elements. Any past-the-end iterator remains valid.

Contents

[edit] Parameters

(none)

[edit] Return value

(none)

[edit] Complexity

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

[edit] Example

#include <algorithm>
#include <iostream>
#include <list>
 
int main()
{
    std::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 << "\nSize=" << container.size() << '\n';
 
    std::cout << "Clear\n";
    container.clear();
 
    std::cout << "After clear:";
    std::for_each(container.begin(), container.end(), print);
    std::cout << "\nSize=" << container.size() << '\n';
}

Output:

Before clear: 1 2 3
Size=3
Clear
After clear:
Size=0

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


[edit] See also

erases elements
(public member function) [edit]