c++ 单例模式

#include <iostream>

using namespace std;

template <class T>
class Instance
{
public:
    static T *getInstance()
    {
        if(m_instance == NULL)
        {
            m_instance = new T();
        }
        return m_instance;
    }

    static void delInstance()
    {
        if(m_instance)
        {
            delete m_instance;
            m_instance = NULL;
        }
    }

protected:
    Instance(){}
    ~Instance(){}

    static T *m_instance;

private:
    //把复制构造函数和=操作符也设为私有,防止被复制
    Instance & operator =(const Instance &) = delete;
    Instance(const Instance &) = delete;   
};

template <class T>
T *Instance<T>::m_instance;

应用：

//不能被继承 单例模式应用
class Ins_test : public Instance<Ins_test>
{
public:
    Ins_test();

    void test();

    void add(int a, int b);

    //C++中初始化struct结构体
    struct hello_
    {
        int a;
        int b;

        hello_(){
            a = 10;
            b = 20;
        }
    }Hello;
};

#include <iostream>
#include ""

using namespace std;

Ins_test::Ins_test()
{

}

void Ins_test::test()
{
    cout<<"this is Instance test"<<endl;
}

void Ins_test::add(int a, int b)
{
    cout<<"sum = "<<a+b<<endl;
}

#include <iostream>
#include ""

using namespace std;

int main()
{
    cout << "Hello World!" << endl;

    Ins_test ins;

    Instance<Ins_test>::getInstance()->test();

    Instance<Ins_test>::getInstance()->add(ins.Hello.a, ins.Hello.b);


    system("pause");

    return 0;
}