在作用域中声明对象时，优先级队列是否为空？ [关闭]

Question

我在main中声明了一个优先级队列，并且在通过if语句满足某些条件时，我使用emplace将一个对象添加到队列中。不幸的是，在if语句退出时，队列似乎是空的。我检查了我的队列是否根本没有添加对象，看来在范围内，对象在队列中。我将粘贴一些我在这里使用的代码。对不起，如果这是一个愚蠢的问题，或者我使用这个网站是错误的，我知道这里的规则有多严格，但我在网站和其他地方搜索了答案。

     int main()
{
int control= 0;

while (control!= -1)
{
int menue_control = 0;
priority_queue<object> neg;
priority_queue<object> pos;
priority_queue<double> test;

cout << "\n pos Empty? " << pos.empty();//1
cout << "\n negEmpty? " << neg.empty();//1
cout << "\n testEmpty? " << test.empty();//1
   //after I run though the if statements once, these return to be empty


std::cout << "\nmenu stuff: Quit\n\n";
std::cin >> menu;
if (menu == 1)
{
    std::cout << "You have selected first Menu option:\n ";
    std::cout << "\nSubmenu:Enter 1 to do OT1 or enter 2 for OT2 ";
    int OT;
    std::cin >> OT;
    string name;
    int num;
    double val;
    if (OT== 1)
    {

        std::cout << "name: ";
        std::cin >> name;
        std::cout << "Enter number : ";
        std::cin >> num;
        std::cout << "Enter 1 for thing, enter 2 for other thing: ";
        int aaa;
        std::cin >> aaa;
        if (aaa== 1)
        {
            std::cout << "Enter val:";
            std::cin >> val;
            pos.emplace(name, num, val);
            test.emplace(val);

            cout << "\n posEmpty? " << pos.empty();//0
            cout << "\n neg Empty? " << neg.empty();//1
            cout << "\n test Empty? " << test.empty();//0

            int difference;
            if (!pos.empty() && !neg.empty()) {
                diff= neg.top() - pos.top();
                if (diff> 0)
                {
                    neg.emplace(name, diff, val);
                }
                if (diff< 0)
                    {
                    pos.emplace(name, -1 * diff, val);
                    }
                    else
                    {
                        std::cout << "done:\n";
                    }
                }

            }
        if (aaa== 2)
        {

        }


    }
    if (OT== 2)
    {

        std::cout << "Enter name: ";
        std::cin >> name;

        std::cout << "Enter number  ";
        std::cin >> num;
        std::cout << "Enter 1 for thing, enter 2 for other thing: ";
        int aaa;
        std::cin >> aaa;
        if (aaa== 1)
        {
            std::cout << "Etner selling price: ";
            std::cin >> val;
            neg.emplace(name, num, val);
            test.emplace(val);


            cout << "\n pos Empty? " << pos.empty();//1
            cout << "\n neg Empty? " << neg.empty();//0
            cout << "\n tes Empty? " << tes.empty();//0


            if (!pos.empty() && !neg.empty()) {

                int diff = pos.top() - neg.top();
                std::cout << "GOT HERE NOW!";

                if (difference > 0)
                {


                    neg.emplace(name, diff, val);
                }
                if (diff< 0)
                {

                    pos.emplace(name, -1 * diff, val);
                }
                else
                {
                    std::cout << "order completely filled:\n";
                }
            }
        }
        if (aaa== 2)
        {
               //do stuff
        }

    }

    }   
//A bunch of if menu statements here that are empty     
    if (menu == 6) { control= -1; }
}
return 0;
}

Answer 1

当while循环结束时，优先级队列超出范围。在他看来，你无法获得它的价值。

我很惊讶它为你编译，它不会在这里。你应该用-Wall编译它，并摆脱所有的错误和警告。这会显示您的错误。