单例模式看起来也蛮简单的，就是在系统中只允许产生这个类的一个实例，既然这么简单，就直接贴代码了。更详细的内容及说明可以参考原作者博客：cbf4life.cnblogs.com。

3.1.解释

main()，大臣

CEmperor，需要单例的类

说明：很多大臣拜见的皇帝，只有一个。体现在面向对象方面，CEmperor定义一个静态指针，和一个静态函数，私有化构造函数、析构函数、构造函数复制、重载赋值语句。

注意：线程安全，采用互斥体的方式实现。

看代码：

//Emperor.h

#pragma once
#include <iostream>
using std::cout;
using std::endl;
using std::string;
class CEmperor
{
public:static CEmperor * GetInstance();static void ReleaseInstance();void EmperorInfo(void);void SetEmperorTag(string tag);
private:CEmperor(void);virtual ~CEmperor(void);CEmperor(const CEmperor&);CEmperor& operator=(const CEmperor&);static CEmperor *m_pEmperor;static HANDLE m_pMutex;string m_EmperorTag;class CGarbo{public:CGarbo(){cout << "Create Garbo" << endl;}~CGarbo(){cout << "Destroy Garbo" << endl;if (NULL != m_pEmperor){WaitForSingleObject(m_pMutex, INFINITE);if (NULL != m_pEmperor){cout << "Remove instance" << endl;delete m_pEmperor;m_pEmperor = NULL;}ReleaseMutex(m_pMutex);}if (NULL != m_pMutex){cout << "Delete mutex" << endl;CloseHandle(m_pMutex);m_pMutex = NULL;}}};static CGarbo m_Garbo;
};
//Emperor.cpp

#include "StdAfx.h"
#include "Emperor.h"
#include <iostream>
using std::cout;
using std::endl;
using std::string;
CEmperor* CEmperor::m_pEmperor = NULL;
HANDLE CEmperor::m_pMutex = CreateMutex(NULL, FALSE, NULL);
CEmperor::CGarbo CEmperor::m_Garbo;
CEmperor::CEmperor(void)
{cout << "Create CEmperor Instance" << endl;
}
CEmperor::~CEmperor(void)
{cout << "Destroy CEmperor Instance and release its resource" << endl;
}
void CEmperor::EmperorInfo(void)
{char msgBuffer[50] = { 0 };sprintf_s(msgBuffer, 50, "皇ê帝?某3某3某3... ...(%s).", m_EmperorTag.c_str());string msg(msgBuffer);cout << msg.c_str() << endl;
}
CEmperor* CEmperor::GetInstance()
{if (NULL == m_pEmperor){WaitForSingleObject(m_pMutex, INFINITE);if (NULL == m_pEmperor)m_pEmperor = new CEmperor();ReleaseMutex(m_pMutex);}return m_pEmperor;
}
void CEmperor::ReleaseInstance()
{if (NULL != m_pEmperor){WaitForSingleObject(m_pMutex, INFINITE);if (NULL != m_pEmperor){delete m_pEmperor;m_pEmperor = NULL;}ReleaseMutex(m_pMutex);}
}
void CEmperor::SetEmperorTag( string tag )
{m_EmperorTag = tag;
}
//Singleton.cpp

#include "stdafx.h"
#include "Emperor.h"

void DoIt()

{

    CEmperor *pEmperor1 = CEmperor::GetInstance();pEmperor1->SetEmperorTag("95");pEmperor1->EmperorInfo();CEmperor *pEmperor2 = CEmperor::GetInstance();pEmperor2->EmperorInfo();CEmperor *pEmperor3 = CEmperor::GetInstance();pEmperor3->EmperorInfo();CEmperor *pEmperor4 = pEmperor3;pEmperor4->EmperorInfo();CEmperor *pEmperor5 = NULL;pEmperor5 = pEmperor4;pEmperor5->EmperorInfo();CEmperor::ReleaseInstance();

}

int _tmain(int argc, _TCHAR* argv[])

{

    DoIt();

    _CrtSetDbgFlag(_CRTDBG_LEAK_CHECK_DF | _CRTDBG_ALLOC_MEM_DF);_CrtDumpMemoryLeaks();return 0;
}

单例模式比较简单，但在项目中使用的时候，需要明确只调用CEmperor的GetInstance函数来获取实例。在C#里有更简单的方法，那就是声明只读的静态变量，比C++简单多了。但C++更吸引人们去研究，这就是软件研发的乐趣吧。