为了解决内存泄漏问题，C++标准库内包含了智能指针，shared_ptr是其中的一种。

#include<iostream>
#include<memory>
using namespace std;

int main()
{
	int *pa = new int(1);
	shared_ptr<int> sp = make_shared<int>(*pa);
	shared_ptr<int> sp1 = sp;
	cout << pa << endl;
	cout << *sp << " " << *sp1 << endl;
	cout << sp << " " << sp1 << endl;
	cout << sp.get() << " " << sp1.get() << endl;
	cout << sp.use_count() << " " << sp1.use_count() << endl;
	
	cout << endl;
	*pa = 4;
	cout << *sp << " " << *sp1 << endl;
	cout << sp << " " << sp1 << endl;
	cout << sp.get() << " " << sp1.get() << endl;
	cout << sp.use_count() << " " << sp1.use_count() << endl;

	cout << endl;
	*sp = 4;//改变原始指针没用
	cout << *sp << " " << *sp1 << endl;
	cout << sp << " " << sp1 << endl;
	cout << sp.get() << " " << sp1.get() << endl;
	cout << sp.use_count() << " " << sp1.use_count() << endl;

	cout << endl;
	*sp1 = 8;
	cout << *sp << " " << *sp1 << endl;
	cout << sp << " " << sp1 << endl;
	cout << sp.get() << " " << sp1.get() << endl;
	cout << sp.use_count() << " " << sp1.use_count() << endl;

	cout << endl;
	int* p = sp.get();
	*p = 9;
	cout << *sp << " " << *sp1 << endl;
	cout << sp << " " << sp1 << endl;
	cout << sp.get() << " " << sp1.get() << endl;
	cout << sp.use_count() << " " << sp1.use_count() << endl;
	
	cout << endl;
	{
		shared_ptr<int> sp2 = sp1;//作用于完了后就会销毁
		cout << sp.use_count() << " " << sp1.use_count() << " " << sp2.use_count() << endl;
	}
	cout << sp.use_count() << " " << sp1.use_count() << endl;

	system("pause");
	return 0;

}

总结：
传入智能指针的只是值，而不是引用，因此会生成新的变量，导致原始指针pa与sp.get()得到的指针指向的空间不是同一处，因此改变原指针pa指向的内容不会改变智能指针指向的内容。***（为甚么会这样，存在疑问？？？？）***