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std::set<Key,Compare,Allocator>::clear

From cppreference.com
< cpp‎ | container‎ | set
 
 
 
 
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, and 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 <iostream>
#include <string_view>
#include <set>
 
void print_info(std::string_view rem, const std::set<int>& v)
{
    std::cout << rem << "{ ";
    for (const auto& value : v)
        std::cout << value << ' ';
    std::cout << "}\n";
    std::cout << "Size=" << v.size() << '\n';
}
 
int main()
{
    std::set<int> container{1, 2, 3};
    print_info("Before clear: ", container);
    container.clear();
    print_info("After clear: ", container);
}

Output:

Before clear: { 1 2 3 }
Size=3
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 224 C++98 the complexity was log(size()) + N, but N was not defined corrected to 'linear in size()'

[edit] See also

erases elements
(public member function) [edit]