如何防止FormatException和IndexOutOfRangeException

本文关键字：IndexOutOfRangeException FormatException 何防止 | 更新日期: 2023-09-27 18:27:57

当用户在将字符串转换为int时输入错误时，此代码会引发Format Exception。当售出32张门票时，它也没有达到所需的输出"所有头等舱座位都已预订"，它只是引发了一个索引超出范围的异常。如有任何帮助，我们将不胜感激。谢谢

class FirstClassCompartment
{ 
    public void FirstClassTickets()
    {
        bool[] seats = new bool[32];
        List<int> seatsBooked = new List<int>();
        int completeBooking = 0;
        bool quit = false;
        string ticketAmount = "";
        int firstClassSeat = 0;
        int convertedTicketAmount;
        {
            Groups firstClass = new Groups();
            Console.Clear();
            Console.WriteLine("'nWelcome to the First Class booking menu");
            Console.WriteLine("");
            Console.WriteLine("Please enter the amount of tickets you would like to book");
            ticketAmount = Console.ReadLine();
            Console.Clear();
            Console.WriteLine("'nFirst Class booking menu");
                    convertedTicketAmount = Convert.ToInt32(ticketAmount);
                    ticketAmount = firstClass.NumberInGroupFirstClassWest;
        }
        do
        {
            Console.Clear();
            Console.WriteLine("'nFirst Class booking menu");
            Console.WriteLine("");
            Console.WriteLine("Please press 1 to complete your first class booking");
            completeBooking = Int32.Parse(Console.ReadLine());
            switch (completeBooking)
            {
                case 1:
                    if (seatsBooked.Count == 0)
                    {
                        firstClassSeat++;
                        seats[firstClassSeat] = true;
                        seatsBooked.Add(firstClassSeat);
                    }
                    else
                    {
                        do
                        {
                            firstClassSeat++;
                            if (!seatsBooked.Contains(firstClassSeat))
                            {
                                seats[firstClassSeat] = true;
                            }
                        }
                        while (seatsBooked.Contains(firstClassSeat) && seatsBooked.Count < 32);
                        if (seatsBooked.Count < 32)
                        {
                            seatsBooked.Add(firstClassSeat);
                        }
                    }
                    if (seatsBooked.Count > 32)
                    {
                        Console.WriteLine("All seats for first class have been booked");
                        Console.WriteLine("Please press enter to continue...");
                    }
                    else
                    {
                        Console.WriteLine("Your seat: {0}", firstClassSeat + 1);
                        Console.WriteLine("Please press enter to continue...");
                    }
                    Console.ReadLine();
                    break;
                default:
                    Console.WriteLine("'nPlease enter a valid input");
                    quit = true;
                    break;
            }
        } while (!quit);
    }
}

如何防止FormatException和IndexOutOfRangeException

您需要使用Int32.TryParse并检查返回的bool。

看看switch语句中的逻辑，您只处理1的预订。如果用户预订了2个座位怎么办
编辑：对不起，刚刚意识到切换语句是处理菜单，而不是预订数量

您是否需要int的列表以及bool的数组来跟踪已预订的座位数量？你就不能用一个普通的旧int，例如numberOfSeatsBooked吗？然后您可以执行numberOfSeatsBooked += convertedTicketAmount;

我会用非常不同的方式来做这件事。您应该有一个座位类，该类包含预订的布尔值，并迭代该布尔值，而不是一个随机的书籍数组，该数组可能链接到或不链接到预订座位和预订座位数量的随机列表。这里有一个小例子：

public class Seat
{
    public int SeatNo { get; set; }
    public bool FirstClass { get; set ; }
    public bool Booked { get; set; } // could actually be an instance of a booking info class including name and ticket id, etc.
}
public class Flight
{
    public List<Seat> Seats = new List<Seat>();
    private int _lastSeat = 0;
    public void AddSeats(int num, bool firstClass)
    {
        for (int i = 0; i < num; i++)
        {
            _lastSeat++;
            Seats.Add(new Seat { SeatNo = num, FirstClass = firstClass });
        }
    }
    public int BookNextAvailableSeat(bool firstClass)
    {
        foreach (Seat seat in Seats.AsQueryable().Where(x => x.FirstClass == firstClass)
        {
            if (!seat.Booked)
            {
                seat.Booked = true;
                return seat.SeatNo;
            }
        }
        return null;
    }
}

然后你的：

case 1:
    int booking = flight.BookNextAvailableSeat(true);
    if (booking != null)
        Console.WriteLine("Your seat: {0}", booking);
    else
        Console.WriteLine("All seats for first class have been booked");
    Console.WriteLine("Please press enter to continue...");
    break;

当然，您需要实例化航班并使用添加32个座位

Flight flight = new Flight();
flight.AddSeats(32, true);
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