单件模式

单件模式要保证的是：类只能实例化一个对象。

为了保证这点，需要将类的构造函数和析构函数声明为私有类型！

代码如下：

class single
{
private:
    single():m_chs("Hello"){}
    ~single(){}

public:
    void printHello()
    {
        printf("%s\n",m_chs);
    }

public:
    static single* getInstance()
    {
        if (!m_instance) m_instance=new single;
        return m_instance;
    }
    static void release()
    {
        if (m_instance) delete m_instance;
    }

private:
    static single* m_instance;
    const char* m_chs;
};

single* single::m_instance = NULL;


int main(int argc, char* argv[])
{
    single* a = single::getInstance();
    a->printHello();
    single::release();
    return 0;
}