無法使用嵌套指向其他結構的初始化struct

Question

我正在使用定義此結構的第三方庫：

typedef struct
{
    unsigned short nbDetectors;
    //! structure of detector status
    struct DetectorStatus
    {
        unsigned int lastError;         //< last detector internal error
        float temperature;              //< detector temperature
        detector_state state;           //< detector state
        unsigned short mode;            //< detector mode

        struct EnergyStatus
        {
            power_source powerSource;           //< front-end power source
            frontend_position frontendPosition; //< front-end position relative to the docking station

            struct BatteryStatus
            {
                bool present;                   //< battery present or not in the detector
                unsigned short charge;          //< charge level of the battery (in %)
                float voltageLevel;             //< battery voltage level
                float temperature;              //< temperature of the battery
                unsigned short chargeCycles;    //< number of charge/discharge cycles
                unsigned short accuracy;        //< Expected accuracy for charge level (in %)
                bool needCalibration;

            } batteryStatus;

        } * energyStatus;

        struct GridStatus
        {
            detector_grid grid;

        } * gridStatus;

    } * detectorStatus;

} HardwareStatus;

庫使用此結構作為其回調之一傳遞的數據。 所以它是填滿它的庫，我只是閱讀它。 到現在為止還挺好。

但是現在我正在為這個庫處理的設備編寫一個模擬器，所以現在我必須填寫其中一個結構，我無法正確使用它。

我試過這個：

HardwareStatus status;
status.detectorStatus->temperature = 20 + rand() % 10;
e.data = &status;
m_pContext->EventCallback( EVT_HARDWARE_STATUS, &e );

當我編譯時，我得到了：

warning C4700: uninitialized local variable 'status' used

然后我意識到......結構中的指針指向垃圾，很好地捕獲Visual Studio！ 那么我試着從聲明一個最里面的結構（ BatteryStatus ）的實例開始，但那不會編譯...因為它不是typedef（它說沒有定義BatteryStatus類型）？ 所以我很難過......我如何填充結構？

Answer 1

你可以重視它：

HardwareStatus status = {};

如果要實例化BatteryStatus ，可以通過完全限定名稱來實現：

HardwareStatus::DetectorStatus::EnergyStatus::BatteryStatus bs;

Answer 2

如果你想把所有東西放在堆棧上，你應該這樣做：

// Getting structs on the stack initialized to zero
HardwareStatus status = { 0 };
HardwareStatus::DetectorStatus detectorStatus = { 0 };
HardwareStatus::DetectorStatus::EnergyStatus energyStatus = { 0 };
HardwareStatus::DetectorStatus::GridStatus gridStatus = { 0 };

// "Linking" structs
detectorStatus.energyStatus = &energyStatus;
detectorStatus.gridStatus = &gridStatus;
status.detectorStatus = &detectorStatus;

// Now you can fill and use them
status.detectorStatus->temperature = 20 + 3 % 10;
//...

Answer 3

你嘗試將結構設置為0嗎？