为什么我的 C++ 哨兵循环在输入哨兵值后继续？

Question

当我输入字符串 "NOMORE" 时，它会继续到下一行，询问我车速。它仅在完成 for 循环时停止循环。我怎样才能让它在输入 "NOMORE" 时立即停止？谢谢你的帮助。我真的很感激。如果我这样做了，很抱歉浪费了你的时间:(

#include <iostream>
#include <string>
#include <iomanip>

using namespace std;

int main()
{
    string plate;
    int totalCount;
    int ticketCount = 0;
    double speed;
    double base = 150;
    double limit;
    double ticket;
    double overspeed;

    for (totalCount = 0; plate != "NOMORE"; totalCount++)
    {
        cout << "Enter a license plate number  --> ";
        cin >> plate;
        cout << "Enter current vehicle's speed --> ";
        cin >> speed;
        cout << "Enter speed limit in the zone --> ";
        cin >> limit;

        overspeed = speed - limit;

        if (overspeed >= 5 && overspeed <= 20)
        {
            ticket = base + 5 * overspeed;
            cout << "A ticket of " << setprecision(2) << fixed << ticket << " is issued to " << plate << "\n\n";

            ticketCount++;
        }
        else if (overspeed > 20  && overspeed <= 50)
        {
            ticket = base + 10 * overspeed;
            cout << "A ticket of " << setprecision(2) << fixed << ticket << " is issued to " << plate << "\n\n";

            ticketCount++;
        }
        else if (overspeed > 50)
        {
            ticket = base + 1000 + (10 * overspeed);
            cout << "A ticket of " << setprecision(2) << fixed << ticket << " is issued to " << plate << "\n\n";

            ticketCount++;
        }
        else
            cout << "No ticket is issued to " << plate << ".\n\n";
    }

    cout << ticketCount << " out of " << totalCount << " times\n";

    return 0;
}

Answer 1

正如@IgorTandetnik 评论的那样，在获得用户输入后立即添加：

cout << "Enter a license plate number  --> ";
cin >> plate;
if (plate == "NOMORE") break; // add this
cout << "Enter current vehicle's speed --> ";
...

for 循环中的条件仅在迭代之间检查，而不是在每个语句之后检查。此流程图总结了它们的行为方式：

为什么我的 C++ 哨兵循环在输入哨兵值后继续？

Why does my C++ sentinel loop continue after the sentinel value is entered?

c++

loops

sentinel