C++ 程序停止中循环，没有错误

Question

我正在开发一个医院模拟程序，其中患者按严重程度排序并放置在相应的队列中。当我调试它时，一切似乎都工作正常，但由于某种原因，它在随机数量的循环后停止。我没有收到任何错误——我的程序只是在循环中退出。什么可能导致这种情况发生？

priority_queue<Hospital_Visit> queue1, queue2;
vector<int> nurse_time_vector, doctor_time_vector;
vector<Hospital_Visit> current_hospital_visit;

for (int i = 0; i < master_hospital_visit.size(); i++){ //make a copy of the master_hospital_visit to manipulate
    current_hospital_visit.push_back(master_hospital_visit[i]);
}



if (num_nurses>0)
    nurse->set_minute(0);
if (num_doctors>0)
    doctor->set_minute(0);

int treatment;

map<string, vector<Hospital_Visit>>::iterator it;

srand(time(NULL));

bool hour_changed = true;

do{

    if (hour_changed){ //update queues with new hour's patients added to end
        for (int i = 0; i < current_hospital_visit.size(); i++){
            if (current_hospital_visit[i].get_hour() > current_hour){
                break;
            }
            if (current_hospital_visit[i].get_hour() <= current_hour)
            {
                if (current_hospital_visit[i].get_severity() <= 10) // For nurses
                {
                    queue1.push(current_hospital_visit[i]);
                    current_hospital_visit.erase(current_hospital_visit.begin() + i);
                }
                else // for doctors
                {
                    queue2.push(current_hospital_visit[i]);
                    current_hospital_visit.erase(current_hospital_visit.begin() + i);
                }
            }
        }
    }

    hour_changed = false;


        if (nurse->get_minute() != nurse->get_max_time() && queue1.size() != 0 && queue1.top().get_hour() <= current_hour && num_nurses > 0)
        {
            treatment = (rand() % 11) + 1;

            queue1.top().set_treatment_time(treatment);

            queue1.top().set_day(current_hour / 24);

            queue1.top().set_hour(current_hour);

            nurse->set_minute(treatment);

            queue1.top().set_wait_time(current_hour - queue1.top().get_hour() + treatment);

            queue1.top().set_medic(false);


            queue1.top().set_severity(queue1.top().get_severity() - (current_hour - queue1.top().get_hour()));


            it = patients_map.find(queue1.top().get_name());
            if (it == patients_map.end())
            {
                vector<Hospital_Visit> patient_visits;

                patient_visits.push_back(queue1.top());

                patients_map.insert(make_pair(queue1.top().get_name(), patient_visits));
            }
            else
            {
                it->second.push_back(queue1.top());
            }
            queue1.pop();
        }
        else if (queue1.size() == 0 && num_nurses > 0) //was !=
        {
            nurse_time_vector.push_back(nurse->get_max_time() - nurse->get_medic_hour());
        }

        if (doctor->get_medic_hour() != doctor->get_max_time() && queue2.size() != 0 &&
            queue2.top().get_hour() <= current_hour && num_doctors > 0)
        {
            treatment = (rand() % 21) + 1;

            queue2.top().set_treatment_time(treatment);

            queue2.top().set_day(current_hour / 24);

            queue2.top().set_hour(current_hour);

            doctor->set_minute(treatment);

            queue2.top().set_wait_time(current_hour - queue2.top().get_hour() + treatment);

            queue2.top().set_medic(true);

            queue2.top().set_severity(queue2.top().get_severity() - (current_hour - queue2.top().get_hour()));

            it = patients_map.find(queue2.top().get_name());
            if (it == patients_map.end())
            {

                vector<Hospital_Visit> patient_visits;

                patient_visits.push_back(queue2.top());

                patients_map.insert(make_pair(queue2.top().get_name(), patient_visits));
            }
            else
            {

                it->second.push_back(queue2.top());
            }
            queue2.pop();
        }

        else if (doctor->get_minute() != doctor->get_max_time() && queue1.size() != 0 && queue2.size() == 0
            && queue1.top().get_hour() <= current_hour && num_doctors > 0){

            treatment = (rand() % 21) + 1;

            queue1.top().set_treatment_time(treatment);

            queue1.top().set_day(current_hour / 24);

            queue1.top().set_hour(current_hour);

            doctor->set_minute(treatment);

            queue1.top().set_wait_time(current_hour - queue1.top().get_hour() + treatment);

            queue1.top().set_medic(true);

            queue1.top().set_severity(queue1.top().get_severity() - (current_hour - queue1.top().get_hour()));

            it = patients_map.find(queue1.top().get_name());
            if (it == patients_map.end())
            {
                vector<Hospital_Visit> patient_visits;
                patient_visits.push_back(queue1.top());
                patients_map.insert(make_pair(queue1.top().get_name(), patient_visits));
            }
            else
            {
                it->second.push_back(queue1.top());
            }
            queue1.pop();

        }

        if ((doctor->get_minute() <= doctor->get_max_time() + 20 && doctor->get_minute() >= doctor->get_max_time()-5) 
            || (queue1.size() == 0 && queue2.size() == 0))
            { // if the max time is reached or the queues are empty, then change the hour

            current_hour++;
            hour_changed = true;

            if (num_nurses>0)
                nurse->set_minute(0);
            if (num_doctors>0)
                doctor->set_minute(0);

            }

} while (current_hour != 169);

Answer 1

看一下这个循环:

for (int i = 0; i < current_hospital_visit.size(); i++){
    ...
    if (...)
    {
        current_hospital_visit.erase(current_hospital_visit.begin() + i);
    }
    ...
}

它不会检查每个元素。假设 i 为 3，并且 if 条件为 true。元素 3 被删除，使元素 4 成为新元素 3。但在下一次迭代中，i 会递增并变为 4，因此这个新元素 3 将永远不会被测试。

一个可能的解决方案是在删除某些内容时递减 i:

for (int i = 0; i < current_hospital_visit.size(); i++){
    ...
    if (...)
    {
        current_hospital_visit.erase(current_hospital_visit.begin() + i);
        i--;
    }
    ...
}