單例設計模式-懶漢餓漢

#include<iostream>
using namespace std;
class Single_Lazy
{
public:
    static Single_Lazy *getInstance()
    {
        if (s == nullptr)
        {
            s = new Single_Lazy();
        }
        return s;
    }
private:
    Single_Lazy()
    {}
    static Single_Lazy *s;
};
Single_Lazy *Single_Lazy:: s = nullptr;
void test1()
{
    Single_Lazy *s1 = Single_Lazy::getInstance();
    Single_Lazy *s3 = Single_Lazy::getInstance();
    Single_Lazy *s2 = Single_Lazy::getInstance();
    if (s1 == s3)
    {
        cout << "指向同一個對象" << endl;
    }
    else
    {
        cout << "指向不是同一個對象" << endl;
    }
}
int main()
{
    test1();
    system("pause");
}      

#include<iostream>
using namespace std;
class Single_Hunger
{
public:
    static Single_Hunger *getInstance()
    {
        return s;
    }
private:
    Single_Hunger()
    {}
    static Single_Hunger *s;
};
Single_Hunger *Single_Hunger::s = new Single_Hunger();
void test1()
{
    Single_Hunger *s1 = Single_Hunger::getInstance();
    Single_Hunger *s2 = Single_Hunger::getInstance();
    if (s1 == s2)
    {
        cout << "指向同一個對象" << endl;
    }
    else
    {
        cout << "指向不是同一個對象" << endl;
    }
}
int main()
{
    test1();
    system("pause");
}