异常处理问题，原因

Question

这是我的主要内容：

int main() {
  Inventory Master;
  bool flag;
  Customer Bob("Bob", "CreditCard.txt");
  Customer Joe("Joe", "CreditCard.txt" );

  Master.firststock( "inventory.txt" );
  vector<Food> temp = Master._Inv;
  cout <<"Hi, What would you like to buy today?" << endl;
  for(unsigned int i=0; i<temp.size(); i++ ) {
    cout << temp[i].name << " " << temp[i].quant << " " << temp[i].price << endl;
  }
  cout <<"n";
  Food Apple("Apples", .99, 10);
  Food Orange("Oranges", .99, 10);
  Food Chip("Chips", 3.00, 10);
  cout <<"nHi Bob" << endl;
  flag = Bob.addCart(Apple, 7, &Master);
  cout <<"Bob's total purchases are Currently: n";
  Bob.report();
  flag = Bob.addCart(Orange, 2, &Master);
  flag = Bob.addCart(Chip, 2, &Master);
  Bob.report();
  flag = Bob.removeCart();
   Bob.report();
  cout <<"Bob, ";
  flag = Bob.checkout(&Master);

以下是我实现的从矢量中删除食物的步骤_Cart：

bool Customer::removeCart() {
  bool flag;
  int q = 0;
  unsigned int i=0;
  string remove;
  cout << "nWhat would you like to remove and how much would you like to remove?" << endl;
  cin >> remove >> q;
 for (i =0; i < _Cart.size(); i++) {
  if(remove == _Cart[i].name) {
      if (q >= 0) {
    _Cart[i].quant -= q;
    //inv->_Inv[i].quant += q;
    cout <<"nYou removed " << q << " " << remove <<" In your cartn" << endl;
    return true;
      }
      if  (q < 0) {
          cout << "Invalid number of " << remove << " being removed.n" << endl;
          return true;
      }
  }
  else {      
  try {
    throw remove;
}
  catch (string param) {
    cout << "n" << remove << " doesn't exist in your cartn" << endl;
        }
        return true;
    }
 }

我的标题包含函数removeCart:

class Customer {
  public:
   Customer(string n, string fileName);
    ~Customer() { _Cart.clear(); };
    bool addCart(Food f, int q, Inventory* inv);
    bool removeCart();
    void report(); 
    bool checkout(Inventory* inv); 
  protected:
    string remove;
    string name;
    int q;
    int card;
    double balance;
    CreditCard _CC(int card,double balance);
    vector<Food> _Cart;
};

现在，出于某种原因，当我调用removeCart时，输入"Apples"有效，但我注意到我制作了一个名为Apple的食物对象，所以不确定为什么输入"Apple"而不是"Apple"有效。同样，当我尝试"橙色"或"芯片"时，会显示异常，但正如你所看到的，我将芯片和橙色添加到了Bob的购物车中。我很感激你的帮助。

Answer 1

您正在创建一个名为Apple的对象，该对象包含一个std:：string类型的成员，该成员包含字符"Apples"。只有你的编译器知道你调用了一个对象Apple，但你的程序会将字符串"Apples"与你的输入进行比较。Orange和Chip也是如此。

Answer 2

您已经在代码中的某个位置声明了一个名为Apple的对象。

然后，实例化了Apple类的实例，并将Apple::name成员设置为字符串'Apples'。

您不是在将输入与类名进行比较，而是在将输入与Apple类的成员数据进行比较。