stl::forward_list

#include <iostream>#include <forward_list>using std::cout;using std::endl;using std::forward_list;void print(const forward_list<int>& src){    for(const int& x : src)        cout << x << " ";    cout << endl;}int main(){    forward_list<int> first;    cout << "first :";    print(first);    forward_list<int> second(4);    cout << "second :";    print(second);    forward_list<int> third(3,77);    cout << "third :";    print(third);    forward_list<int> fourth(third.begin(),third.end());    cout << "fourth :";    print(fourth);    forward_list<int> fifth(fourth);    cout << "fifth :";    print(fifth);    forward_list<int> sixth(std::move(fifth));    cout << "sixth :";    print(sixth);    // fifth 已经没有元素了，不能输出,但可以调用这句话    print(fifth);       forward_list<int> seventh = {3,52,25,90};    cout << "seventh :";    print(seventh);    return 0;}