错误C2228：'。Alloc'的左边必须有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（参见类中的最后一个函数）。所以我写这个程序：

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

但它给出了错误，其中一个是：

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

语法是否正确？为什么要上课？什么是正确的方法？

Answer 1

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

除此之外，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是指针。

Answer 2

lBuffer是PvBuffer*，您需要创建和参与：

lBuffer = new PvBuffer()
lBuffer->Alloc(....);