std::map<Key,T,Compare,Allocator>::clear
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
#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
| erases elements (public member function) |
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