Question

用适当的方法在C ++中实现类和枚举。

class CrossingGateRoad {
    public:
        boolean PowerOn(byte relayNumber) {
            digitalWrite(relayNumber, RELAY_ON);
            return true;
        }
        boolean PowerOff(byte relayNumber) {
            digitalWrite(relayNumber, RELAY_OFF);
            return true;
        }
};

然后我尝试按如下方式创建枚举：

enum {
    CROSSINGZONE_CLEAR, // no train in crossing area, also initialized state
    CROSSINGZONE_OCCUPIED, // train detected by the entry sensor
    CROSSINGZONE_EXITING  // train detected by the exit sensor, when sensor clears, state = CLEAR
};

在C＃中，我会命名我的枚举并指定值：

public enum CommodityIndexSector
{
    Currency = 1,
    StockIndex = 2,
    GovernmentBond = 3,
    Metals = 4,
    Energy = 5,
    Grains = 6,
    Softs = 7,
    Meats = 8,
    Other = 9
}

我会这样访问.... enumname.enumvalue。我不能100％确定课程看起来也不错。

Answer 1

在c ++中enum值出现在其外部范围内。如果你有

enum {
    CROSSINGZONE_CLEAR, // no train in crossing area, also initialized state
    CROSSINGZONE_OCCUPIED, // train detected by the entry sensor
    CROSSINGZONE_EXITING  // train detected by the exit sensor, when sensor clears, state = CLEAR
};

几乎等同于#define值。

要在其他地方指定枚举类型，您需要为其命名：

enum CrossingZones {
  // ^^^^^^^^^^^^^
    CROSSINGZONE_CLEAR, // no train in crossing area, also initialized state
    CROSSINGZONE_OCCUPIED, // train detected by the entry sensor
    CROSSINGZONE_EXITING  // train detected by the exit sensor, when sensor clears, state = CLEAR
};

并且您可以引用特定的枚举类型：

CrossingZones crossingZones = CROSSINGZONE_CLEAR;

关于值的更直观的声明是使用与当前标准相同的枚举类：

enum class CrossingZones {
  // ^^^^^
    CROSSINGZONE_CLEAR, // no train in crossing area, also initialized state
    CROSSINGZONE_OCCUPIED, // train detected by the entry sensor
    CROSSINGZONE_EXITING  // train detected by the exit sensor, when sensor clears, state = CLEAR
};

并使用范围：

CrossingZones crossingZones = CrossingZones::CROSSINGZONE_CLEAR;
                           // ^^^^^^^^^^^^^^^

Answer 2

在c ++ 11中，您现在可以使用enum class，也可以为其指定值。但是，您需要使用强制转换来获取值。

enum class Crossing_zone {
    clear = 0,
    occupied = 2,
    exiting = 1
};

int main()
{
    auto myenumvar = Crossing_zone::occupied;
    return 0;
}

Answer 3

您可以使用以下代码声明枚举：

typedef enum {
    CROSSINGZONE_CLEAR, // no train in crossing area, also initialized state
    CROSSINGZONE_OCCUPIED, // train detected by the entry sensor
    CROSSINGZONE_EXITING  // train detected by the exit sensor
} EnumName;

abd然后通过以下代码访问其值：

EnumName::CROSSINGZONE_OCCUPIED

在C ++中使用类和枚举

3 个答案: