#include <iostream>#include <memory>#include <string> int main(){// default allocator for ints    std::allocator<int> alloc1; // demonstrating the few directly usable members    static_assert(std::is_same_v<int, decltype(alloc1)::value_type>);int* p1= alloc1.allocate(1);// space for one int    alloc1.deallocate(p1,1);// and it is gone // Even those can be used through traits though, so no needusing traits_t1=std::allocator_traits<decltype(alloc1)>;// The matching trait    p1= traits_t1::allocate(alloc1,1);    traits_t1::construct(alloc1, p1,7);// construct the intstd::cout<<*p1<<'\n';    traits_t1::deallocate(alloc1, p1,1);// deallocate space for one int // default allocator for strings    std::allocator<std::string> alloc2;// matching traitsusing traits_t2=std::allocator_traits<decltype(alloc2)>; // Rebinding the allocator using the trait for strings gets the same type    traits_t2::rebind_alloc<std::string> alloc_= alloc2; std::string* p2= traits_t2::allocate(alloc2,2);// space for 2 strings     traits_t2::construct(alloc2, p2,"foo");    traits_t2::construct(alloc2, p2+1,"bar"); std::cout<< p2[0]<<' '<< p2[1]<<'\n';     traits_t2::destroy(alloc2, p2+1);    traits_t2::destroy(alloc2, p2);    traits_t2::deallocate(alloc2, p2,2);}

7foo bar