c++ - C++中未声明的标识符(错误C2065)

我正在实现头文件“IVideoPlayer.h”，并且创建了一个抽象类“IVideoPlayer”。

class IVideoPlayer
{

public:
// Initialization
virtual bool Load(const char* pFilePath, bool useSubtitles = false) = 0;
    virtual bool Start() = 0;
    virtual bool Stop() = 0;
    //....
};

其功能在文件“VideoPlayer.cpp”中定义

#include "stdafx.h"
#include "IVideoPlayer.h"
#include <dshow.h>


HRESULT hr = CoInitialize(NULL);
IGraphBuilder *pGraph = NULL;
IMediaControl *pControl = NULL;
IMediaEvent   *pEvent = NULL;

class VideoPlayer:public IVideoPlayer
{
public:

    bool Load(const char* pFilePath, bool useSubtitles = false)
    {
        EPlaybackStatus var1 = PBS_ERROR;
        // Initialize the COM library.

        if (FAILED(hr))
        {
            printf("ERROR - Could not initialize COM library");
            return 0;
        }

        // Create the filter graph manager and query for interfaces.
    hr = CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER,
            IID_IGraphBuilder, (void **)&pGraph);
        if (FAILED(hr))
        {
        printf("ERROR - Could not create the Filter Graph Manager.");
            return 0;
        }

        hr = pGraph->QueryInterface(IID_IMediaControl, (void **)&pControl);
        hr = pGraph->QueryInterface(IID_IMediaEvent, (void **)&pEvent);

        // Build the graph. IMPORTANT: Change this string to a file on your system.
        hr = pGraph->RenderFile(L"G:\edit.wmv", NULL);
        return 0;

    }

    bool Start()
    {
        if (SUCCEEDED(hr))
        {
            // Run the graph.
            hr = pControl->Run();
            if (SUCCEEDED(hr))
            {
                // Wait for completion.
                long evCode;
                pEvent->WaitForCompletion(INFINITE, &evCode);

        // Note: Do not use INFINITE in a real application, because it
                // can block indefinitely.
            }
        }
        return 0;

    }

    bool Stop()
    {
        pControl->Release();
        pEvent->Release();
        pGraph->Release();
        CoUninitialize();
        return 0;

    }
};

并检查头文件，我创建了文件sample.cpp

#include "stdafx.h"
#include "IVideoPlayer.h"
#include <stdio.h>
#include <conio.h>



int main(void)
{
VideoPlayer h;
h.Load("G:\hila.wmv");
getch();
return 0;
}

错误是:

Error   1 error C2065: 'VideoPlayer' : undeclared identifier
Error   2 error C2146: syntax error : missing ';' before identifier 'h'
Error   3 error C2065: 'h' : undeclared identifier
Error   4 error C2065: 'h' : undeclared identifier
Error   5 error C2228: left of '.Load' must have class/struct/union

为什么编译器将其显示为未声明的标识符？
任何帮助都可以接受。预先谢谢你

最佳答案

您绝不会包含任何定义std命名空间的头文件，因此，(未定义)命名空间的using会导致错误。您也不包含任何定义VideoPlayer类的头，主要是因为您决定将类定义放在源文件中，而不是头文件中。

以上解释了两个第一个错误。剩下的错误是由于第二个错误(未定义VideoPlayer)导致的后续错误。

您需要制作一个放置VideoPlayer类定义的头文件，非常类似于IVideoPlayer类的头文件。您将VideoPlayer成员函数的实现放入源文件中。然后将头文件包含在需要VideoPlayer类的源文件中。

videoplayer

c++ - C++中未声明的标识符(错误C2065)