从条件陈述中获取计数

Question

我正在尝试使用count变量来计算条件为真的次数，并将其用于比较。但是当我编译它时，count总是为0，它永远不会增加，即使条件为真。

foreach (ReservationType requestReservation in RequestReservation)
{
    List<String> DateList = CreateDateList(requestReservation.StartDate, requestReservation.numDays);

    foreach (Inventory inventory in RoomInventory)
    {
        if (requestReservation.hotelId == inventory.HotelId)
        {
            if (requestReservation.roomType == inventory.RoomType)
            {
                int count = 0;
                int i = 0;
                if (DateList[i] == inventory.Date && inventory.Quantity > 0)
                {
                    count++;

                    if (requestReservation.numDays == count)
                    {
                        requestReservation.reservationId = reservationid;
                        requestReservation.result = ReservationType.ReservationResultType.Success;
                        inventory.Quantity--;
                    }
                    else 
                    {
                        requestReservation.result = ReservationType.ReservationResultType.RoomNotAvailable;

                    }
                }
            }
        }                      
   }
    reservationid++;
}

Answer 1

在循环的scope之外定义count

int count = 0;
foreach (ReservationType requestReservation in RequestReservation)
{
    List<String> DateList = CreateDateList(requestReservation.StartDate, requestReservation.numDays);
    foreach (Inventory inventory in RoomInventory)
    {
        // Rest of code
    }
}

参见Variable and Method Scope in Microsoft .NET - 变量仅针对循环的范围定义，并且在范围的末尾删除对它的任何引用。通过在循环之前定义它，它可用于外部作用域和任何嵌套作用域

请注意，当你定义count时，int i = 0;定义错误，你实际上总是在你的if语句中检查0的相同位置：

//i is always 0
if (DateList[i] == inventory.Date && inventory.Quantity > 0)

Answer 2

你已经在循环中声明了计数，并且每次将它声明出循环并且它将会起作用时它变为0

Answer 3

在第一个foreach循环之前定义计数变量。