table of contents
std::map::clear(3) | C++ Standard Libary | std::map::clear(3) |
NAME¶
std::map::clear - std::map::clear
Synopsis¶
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.
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 <map>
int main()
{
std::map<int, char> container{{1, 'x'}, {2, 'y'}, {3, 'z'}};
auto print = [](std::pair<const int, char>& n) {
std::cout << " " << n.first << '(' <<
n.second << ')';
};
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(x) 2(y) 3(z)
Size=3
Clear
After clear:
Size=0
See also¶
erase erases elements
(public member function)
2022.07.31 | http://cppreference.com |