Question

#ifndef DATACENTER_H_
#define DATACENTER_H_

#include <map>
#include <list>
#include <string>

#include "LiLo/SoundInfo.h"
#include "MutexCondition.h"
#include "UserInfo.h"

using namespace std;

class DataCenter : MutexCondition{

private:

    map<long long, list<SoundInfo *> > m_soundListMap;


    void add(long long deviceId, SoundInfo* soundInfo);

public:

    DataCenter();
    virtual ~DataCenter();

    static void addSoundInfo(long long deviceId, SoundInfo *soundInfo);

};

#endif /* DATACENTER_H_ */

DataCenter.cpp file

#include "DataCenter.h"

DataCenter::DataCenter() {
    // TODO Auto-generated constructor stub

}

DataCenter::~DataCenter() {
    // TODO Auto-generated destructor stub
}

void DataCenter::addSoundInfo(long long deviceId, SoundInfo *soundInfo){
    add(deviceId, soundInfo);
}

void DataCenter::add(long long deviceId, SoundInfo *soundInfo){
    list<SoundInfo*>& info_list = m_soundListMap[55];
}

I am trying to access the function call addSoundInfo from other classes so I have set this as static. Since the m_soundListMap is not a static so I think I need another function to access to the local data structure.

Inside of the static function, I call add function to add SoundInfo to the list. However, I am getting an error in the static function and it says “Can not call member function …. without object”.

How do I fix this problem? Thanks in advance..

Answer 1

If you want to access addSoundInfo from other classes, you need to make it public, or make those other classes friends of DataCenter. static has nothing to with access control.

A static function is not bound to an instance of the class it belongs to, and thus can not access members of that class (it also can not call member-functions). If you really want to access members from a static function, you have to pass an instance of the class as argument the the static function explicitly.

If you struggle with such basic concepts, you should read a good book.