#include <iostream>
using namespace std;
#include <mutex>
/*
    懶漢式
*/
class SingleTon {
private:
    SingleTon() {
        
    }
private:
    static SingleTon* ton;
    static int count;
    static mutex mu;
public:
    static SingleTon* getInstance() {
        if (ton == NULL) {
            mu.lock();
            if (ton == NULL)
            {
                ton = new SingleTon;
            }
            mu.unlock();
        }
        return ton;
    }

    void add() {
        count++;
        cout<<count<<endl;
    }


};
//靜態(tài)變量的初始化放在類的外部
//？因為類定義的時候并沒有分配內存，靜態(tài)變量也不能等到創(chuàng)建對象的時候才分配內存，必須提前分配
SingleTon* SingleTon::ton = NULL;
int SingleTon::count = 1;
mutex SingleTon::mu;


/////////////////////////////////////////////////////////////////////////////////

/*
    餓漢式
*/
class SingleTon2 {
private:
    SingleTon2() {
    }
private:
    static SingleTon2* ton;
    static int count;
public:
    static SingleTon2* getInstance() {
        return ton;
    }

    void add() {
        count++;
        cout << count << endl;
    }


};
//靜態(tài)變量的初始化放在類的外部
//？因為類定義的時候并沒有分配內存，靜態(tài)變量也不能等到創(chuàng)建對象的時候才分配內存，必須提前分配
SingleTon2* SingleTon2::ton = new SingleTon2;
int SingleTon2::count = 1;

void main() {

    SingleTon* s = SingleTon::getInstance();
    s->add();
    SingleTon* s1 = SingleTon::getInstance();
    s1->add();


    SingleTon2* s3 = SingleTon2::getInstance();
    s3->add();
    SingleTon2* s4 = SingleTon2::getInstance();
    s4->add();

    system("pause");
}