C++单件模式（只保留唯一个类对象）

C++单件模式（只保留唯一个类对象）
[user:test] cat main.cpp

/// @file main.cpp

/// @brief

/// EastonWoo

/// 0.01

/// @date 2013-03-10

#include <stdio.h>

#include <memory>

#include <mutex>

class Ctest

{

public:

static Ctest* Instance();

protected: //用protected,而不用public的作用：不能直接申请对象，只能通过Instance()申请

Ctest(){};

virtual ~Ctest(){};

private:

friend class std::auto_ptr<Ctest>; //

static std::auto_ptr<Ctest> m_pInstance; //智能指针，程序退出时会自动释放new Ctest的内存。

static std::mutex m_InstanceMux; //用锁同一时间只能申请一次。安全。

public:

int m_val;

};

std::auto_ptr<Ctest> Ctest::m_pInstance;

std::mutex Ctest::m_InstanceMux;

Ctest* Ctest::Instance()

{

m_InstanceMux.lock();

if(NULL == m_pInstance.get())

{

m_pInstance.reset(new Ctest);

}

m_InstanceMux.unlock();

return m_pInstance.get();

}

int main(int argc, const char *argv[])

{

Ctest* pTest1 = Ctest::Instance();

pTest1->m_val = 1;

Ctest* pTest2 = Ctest::Instance();

pTest2->m_val = 2;

printf("pTest1->m_val = %d\n",pTest1->m_val);

printf("pTest2->m_val = %d\n",pTest2->m_val);

return 0;

}