c++ - 在 C++ 中使用内部类时，不允许使用指向不完整类类型的指针

Question

我有一个类扫描器，其中设备消息被声明为内部的，如下所示。这是scanner.h文件代码：

#pragma once
class CScanner
{
public:
    CScanner(void);


    class CDeviceMessage;

    ~CScanner(void);
};

设备消息类在其方法中出现问题，此指针有错误。它说指向不完整类类型的指针不允许 CDeviceMessage.h。

CDeviceMessage.h 文件代码在这里，我不包括完整的代码，而是函数定义和声明，所以你可能会理解它：

#pragma once
#include "Scanner.h"


class CScanner::CDeviceMessage
{

bool MatchesOtherMessage(CScanner::CDeviceMessage * other);

};

错误出现的 CDeviceMessage.cpp 函数是这样的：

bool CScanner::CDeviceMessage::MatchesOtherMessage(CDeviceMessage *other)
{

    if (other != NULL)
            {
                if ((this->imgMessage != NULL) && (other->imgMessage != NULL))/// here it gives on this pointer error that pointer to incomplete class type is not allowed
                {
                    int timeDiff = this->imgMessage->OnlineMilliseconds
                            - this->imgMessage->OnlineMilliseconds;
                    if ((timeDiff > -20) && (timeDiff < 40))
                    {
                        return true;
                    }
                }
            }
            return false;
}

Answer 1

您在 in 前面缺少一个CScanner::前缀CDeviceMessage *other

bool CScanner::CDeviceMessage::MatchesOtherMessage(CDeviceMessage *other)