#include <cassert>#include <initializer_list>#include <iostream>#include <vector> template<class T>struct S{std::vector<T> v;     S(std::initializer_list<T> l): v(l){std::cout<<"constructed with a "<< l.size()<<"-element list\n";} void append(std::initializer_list<T> l){        v.insert(v.end(), l.begin(), l.end());} std::pair<const T*,std::size_t> c_arr()const{return{&v[0], v.size()};// copy list-initialization in return statement// this is NOT a use of std::initializer_list}}; template<typename T>void templated_fn(T){} int main(){    S<int> s={1,2,3,4,5};// copy list-initialization    s.append({6,7,8});// list-initialization in function call std::cout<<"The vector now has "<< s.c_arr().second<<" ints:\n";for(auto n: s.v)std::cout<< n<<' ';std::cout<<'\n'; std::cout<<"Range-for over brace-init-list:\n";for(int x:{-1,-2,-3})// the rule for auto makes this ranged-for workstd::cout<< x<<' ';std::cout<<'\n'; auto al={10,11,12};// special rule for autostd::cout<<"The list bound to auto has size() = "<< al.size()<<'\n';auto la= al;// a shallow-copy of top-level proxy objectassert(la.begin()== al.begin());// guaranteed: backing array is the same     std::initializer_list<int> il{-3,-2,-1};assert(il.begin()[2]==-1);// note the replacement for absent operator[]    il= al;// shallow-copyassert(il.begin()== al.begin());// guaranteed //  templated_fn({1, 2, 3}); // compiler error! "{1, 2, 3}" is not an expression,// it has no type, and so T cannot be deduced    templated_fn<std::initializer_list<int>>({1,2,3});// OK    templated_fn<std::vector<int>>({1,2,3});// also OK}

constructed with a 5-element listThe vector now has 8 ints:1 2 3 4 5 6 7 8Range-for over brace-init-list:-1 -2 -3The list bound to auto has size() = 3