void Test15() { int k = 3; List l; for(int i = 1; i<=10; ++i) { l.PushBack(i); } l.Print(); cout << "3:" << l.Back_K(k)->_data << endl; k = 10; cout << "10:" << l.Back_K(k)->_data << endl; k = 1; cout << "1:" << l.Back_K(k)->_data << endl; }