/*某商店经销一种货物，货物的购进和卖出以箱为单位，各箱的重量不一样，因此商店需要目前库存的总重量。现在用c++模拟商店货物购进和卖出的情况*/#include
     
      using namespace std;//货物类class Goods{public:    Goods(int w=0){        this->weight = w;    }    int GetW(){        return weight;    }    Goods *next;private:    //重量    int weight;};//商店类class Shop{public:    Shop(int s=0){        this->weights = s;        pHead = NULL;    }    ~Shop(){        if (pHead!=NULL)        {            Goods *pCurrent = pHead;            Goods *pNext = NULL;            while (pCurrent){                pNext = pCurrent->next;                delete pCurrent;                pCurrent = NULL;                pCurrent = pNext;            }        }        weights = 0;    }    //卖出    void SellOut(){        if (pHead==NULL)        {            cout << "商店里已经没有货物了！" << endl;        }        else{            //队列  先进先出            Goods *pCurrent = pHead;            pHead = pHead->next;            delete pCurrent;        }    }    //购进    void Purchase(Goods *&pin){        if (pHead==NULL)        {            //插入第一箱货物            pHead = pin;            weights += pin->GetW();        }        else{            Goods *pCurrent = pHead;            while (pCurrent->next){                pCurrent = pCurrent->next;            }            pCurrent->next = pin;            weights += pin->GetW();        }    }    //查询货物重量    int GetWeight(){        return weights;    }private:    int weights;    Goods *pHead;};void protectA(){    Shop *sp = new Shop();    int indexover = 1;    while (indexover){        int num = 0;        int w = 0;        cout << "请输入操作：" << endl;        cout << "1购进货物" << endl;        cout << "2卖出货物" << endl;        cout << "3查看现有货物重量" << endl;        cout << "按任意键退出" << endl;        cin >> num;        switch (num)        {        case 1:            cout << "请输入货物的重量" << endl;            //备注：在c++中不可以在case语句里定义任意变量,如果非要定义，请外面套上大括号{}            //int ss = 0;            //报错 ： error C2360: “ss”的初始化操作由“case”标签跳过            {                cin >> w;                Goods * g1 = new Goods(w);                sp->Purchase(g1);            }            break;        case 2:            {                sp->SellOut();            }            break;        case 3:            cout << "现有货物的重量是" << sp->GetWeight() << endl;            break;        default:            indexover = 0;            break;        }    }    if (sp!=NULL)    {        delete sp;    }}void main(){    protectA();    system("pause");}