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void clear(); | (noexcept since C++11) (constexpr since C++26) | |
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 iterators are also invalidated.
Contents |
Linear in the size of the container, i.e., the number of elements.
#include <iostream>#include <string_view>#include <deque> void print_info(std::string_view rem,conststd::deque<int>& v){std::cout<< rem<<"{ ";for(constauto& value: v)std::cout<< value<<' ';std::cout<<"}\n";std::cout<<"Size="<< v.size()<<'\n';} int main(){std::deque<int> container{1,2,3}; print_info("Before clear: ", container); container.clear(); print_info("After clear: ", container);}
Output:
Before clear: { 1 2 3 }Size=3After clear: { }Size=0The 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 |
| erases elements (public member function)[edit] |
