单例模式

#ifndef DESIGN_SINGLETON_H_
#define DESIGN_SINGLETON_H_

#include <iostream>

class Singleton
{
private:
    Singleton(){}
public:
    static Singleton* GetInstance();

private:
    static Singleton* g_instance;
};

#endif // DESIGN_SINGLETON_H_

#include "singleton.h"

Singleton* Singleton::g_instance = new Singleton();

Singleton* Singleton::GetInstance()
{
    if (g_instance == 0)
    {
        std::cout << "singleton initing..." << std::endl;
        g_instance = new Singleton();
    }

    return g_instance;
}