Question

I’m trying to create a C++ class which can work as a holder for my project, so have implemented my class members and functions static, but I don’t know why compiler can recognize the _nTriggerMode inside the setTriggerMode.

Here is my header file:

#pragma once
class GrabberOptions
{
private:
    static int _nTriggerMode;
    static int _nExposureInMicroSec;
    static double _dFramesPerSecond;
    static int _nExsysncOn;

public:
    GrabberOptions(void);
    ~GrabberOptions(void);
    static void setTriggerMode(int triggerMode);
    static void setExposureInMicroSec(int exposureMicroSec);
    static void setFramePerSecond(double framePerSec);
    static void setExsysncOn(int exsysncOn);

    static int getTriggerMode();
    static int getExposureInMicroSec();
    static double getFramePerSecond();
    static int getExsysncOn();
};

And here is the .ccp file:

#include "StdAfx.h"
#include "GrabberOptions.h"
 int GrabberOptions::_nTriggerMode;

int GrabberOptions::_nExposureInMicroSec;
double GrabberOptions::_dFramesPerSecond;
int GrabberOptions::_nExsysncOn;
GrabberOptions::GrabberOptions(void)
{
_nTriggerMode = GRABBER_CONTROLLED;
_nExposureInMicroSec = 20;
_dFramesPerSecond = 1000;
_nExsysncOn = 1;
}

GrabberOptions::~GrabberOptions(void)
{
}

void setTriggerMode(int triggerMode){
_nTriggerMode=triggerMode;
}

Please give me some idea of how to use static.

Answer 1

static class member variables must be defined outside of the class definition:

// .h file
class GrabberOptions
{
private:
    static double _dFramesPerSecond; // declaration

// .cpp file
double GrabberOptions::_dFramesPerSecond = 1000; // definition