指向结构错误向量的指针

Question

我正在为移动机器人制作.lib文件。 目前我正在编写扫描蓝牙设备的功能。

功能是：

struct Device
{
     string DeviceName;
     BTH_ADDR DeviceAddress;
};

void ScanForDevices(vector<Device> *Robot)
    {
        m_bt = BluetoothFindFirstRadio(&m_bt_find_radio, &m_radio);

        BluetoothGetRadioInfo(m_radio, &m_bt_info);
        m_search_params.hRadio = m_radio;

        ZeroMemory(&m_device_info, sizeof(BLUETOOTH_DEVICE_INFO));
        m_device_info.dwSize = sizeof(BLUETOOTH_DEVICE_INFO);

        m_bt_dev = BluetoothFindFirstDevice(&m_search_params, &m_device_info);


        int m_device_id = 0;
        char charDeviceName[250];

        do {
                charDeviceName[250]=NULL;
                Robot->push_back(Device()); 
                //WideCharToMultiByte(CP_UTF8,0,m_device_info.szName,-1, charDeviceName,0,NULL, NULL);
                WideCharToMultiByte(CP_UTF8,0,m_device_info.szName,-1, charDeviceName,250,NULL, NULL);
                Robot[m_device_id]->DeviceName=(string)charDeviceName;
                Robot[m_device_id]->DeviceAddress=m_device_info.Address.ullLong;
                m_device_id++;

            } while(BluetoothFindNextDevice(m_bt_dev,&m_device_info));

            BluetoothFindDeviceClose(m_bt_dev);

            BluetoothFindRadioClose(m_bt);
    }

我一直在：

Error   6   error C2819: type 'std::vector<_Ty>' does not have an overloaded member 'operator ->'
Error   7   error C2039: 'DeviceName' : is not a member of 'std::vector<_Ty>'
Error   8   error C2819: type 'std::vector<_Ty>' does not have an overloaded member 'operator ->'
Error   9   error C2039: 'DeviceAddress' : is not a member of 'std::vector<_Ty>'
Error   10  IntelliSense: expression must have pointer type 
Error   11  IntelliSense: expression must have pointer type 

我正在启动C ++，并且我并不熟练使用指针。

欢迎任何帮助。

Answer 1

要按索引访问vector<Device> *Robot元素，请使用以下语法：

(*Robot)[m_device_id]

你的代码应该是：

(*Robot)[m_device_id].DeviceName=(string)charDeviceName;

请注意->替换为. 因为vector元素有Device类型，所以这不是指针。

您现有的代码与以下矢量声明匹配：

vector<Device*> Robot

看到不同。

Answer 2

Robot是指向vector<Device>的指针。 您对指向矢量和矢量元素的访问感到困惑。 要解决此问题，您可以更改：

Robot[m_device_id]->DeviceName=(string)charDeviceName;

至

Robot->at(m_device_id).DeviceName = std::string(charDeviceName);

要么

(*Robot)[m_device_id].DeviceName = std::string(charDeviceName);

建议 ：

更好的解决方案是通过引用而不是指针传递向量。

void ScanForDevices(vector<Device> &Robot)
{
    std::string  charDeviceName;   //<<-- use std::string instead of char array
    Robot[m_device_id].DeviceName = charDeviceName;  //<<-- this is better coding style
}