c++ - 错误 C2228 : left of '.Alloc' must have class/struct/union

Question

我有一个 SDK (GigE C++)，它定义了这样一个类:

class PV_BUFFER_API PvBuffer
 {

public: 

 PvBuffer();
 virtual ~PvBuffer();
 PvPayloadType GetPayloadType() const;
 #ifndef PV_NODEPRECATED
 PvResult Alloc( PvUInt32 aSizeX, PvUInt32 aSizeY, PvPixelType aPixelType );
};

SDK的文档说:

 PvResult PvBuffer::Alloc  ( PvUInt32  aSizeX,  
 PvUInt32  aSizeY,  
 PvPixelType  aPixelType   
 )    

 Allocates memory for this PvBuffer. 

 Parameters:
 [in]  aSizeX  The width of the image, in pixels. See GetWidth.  
 [in]  aSizeY  The height of the image, in pixels. See GetHeight.  
 [in]  aPixelType  The GEV pixel type from which the pixel depth is extracted. For     
 supported pixel types, see PvPixelType.h. 

 Returns:
 Includes:
 PvResult::Code::OK 
 PvResult::Code::NOT_ENOUGH_MEMORY 

我想使用 Alloc 函数(参见类(class)中的最后一个函数)。所以我这样写程序:

 PvBuffer *lBuffer;  //Class name is PvBuffer
 PvResult lResult= lBuffer.Alloc( 1224, 1029,  PVPIXELMONO );

但它给出了错误，其中之一是:

error C2228: left of '.Alloc' must have class/struct/union   

语法是否正确？为什么要上课？正确的做法是什么？

Answer 1

PvBuffer *lBuffer;  //Class name is PvBuffer
PvResult lResult= lBuffer.Alloc( 1224, 1029,  PVPIXELMONO );

抛开这会调用未定义的行为，因为lBuffer 未初始化，您需要:

PvResult lResult= lBuffer->Alloc( 1224, 1029,  PVPIXELMONO );

因为lBuffer是一个指针。