Question

I am working on Visual C++. Can you please help in this syntax .

  class CVisionSystem
  {
    public:
CVisionSystem();
 ~CVisionSystem(void);


int Init();


    private:

 PvDevice device;
// PvStream object
      PvStream stream;
// Buffer

  CustomPipeline *pipeline;

// GEV Parameters
PvGenParameterArray *deviceParams;
    PvGenInteger *parTLLocked;

 };

int CVisionSystem::Init()
 {
 deviceParams = device.GetGenParameters();    
 parTLLocked = dynamic_cast<PvGenInteger *>( deviceParams->Get( "TLParamsLocked" ) );

 }

deviceParms gets valid value, however parTLlocked gets NULL value that leads to an error : “error expression cannot be evaluated, _vfptr CX0030 and mthis CX0076.

What can be the problem of ParTLLocked ?

Answer 1

I am guessing that deviceParams->Get( "TLParamsLocked" ) returns a type that can not be dynamic casted to PvGenInteger *. The return type should be a pointer to either a subclass or a parent class of PvGenInteger(or possibly the same class) for this dynamic_cast to return non-null value.