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

Invalidates any references, pointers, and iterators referring to contained elements.May also invalidate past-the-end iterators.

[edit]Complexity

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

[edit]Example

#include <iostream>#include <string_view>#include <unordered_set> void print_info(std::string_view rem,conststd::unordered_set<int>& v){std::cout<< rem<<"{ ";for(constauto& value: v)std::cout<< value<<' ';std::cout<<"}\n";std::cout<<"Size="<< v.size()<<'\n';} int main(){std::unordered_set<int> container{1,2,3};    print_info("Before clear: ", container);    container.clear();    print_info("After clear: ", container);}

Before clear: { 1 2 3 }Size=3After clear: { }Size=0

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit]See also

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