// https://learn.microsoft.com/en-us/cpp/standard-library/enable-shared-from-this-class?view=msvc-170

#include <memory>

#include <iostream>

#include <cstring>

using namespace std;

struct base

? ? // : public std::enable_shared_from_this<base>

{

? ? char *val;

? ? base(){

? ? ? ? val = new char[1024];

? ? }

? ? ~base(){

? ? ? ? delete []val;

? ? }

? ? // shared_ptr<base> share_more()

? ? base *share_more()

? ? {

? ? ? ? // return shared_from_this();

? ? ? ? return this;

? ? }

};

int main2()

{

? ? // std::shared_ptr<base> sp2;

? ? base *sp2;

? ? {

? ? ? ? // std::shared_ptr<base> sp1 = make_shared<base>();

? ? ? ? base b; base *sp1 = &b;

? ? ? ? sp2 = sp1->share_more();

? ? ? ? std::strncpy(sp1->val, "hello", 1024 - 1);

? ? }

? ? cout << "sp2->val == " << sp2->val << endl;

? ? return 0;

}

---

// https://learn.microsoft.com/en-us/cpp/standard-library/enable-shared-from-this-class?view=msvc-170

#include <memory>

#include <iostream>

#include <cstring>

using namespace std;

struct base

? ? : public std::enable_shared_from_this<base>

{

? ? char *val;

? ? base(){

? ? ? ? val = new char[1024];

? ? }

? ? ~base(){

? ? ? ? delete []val;

? ? }

? ? shared_ptr<base> share_more()

? ? // base *share_more()

? ? {

? ? ? ? return shared_from_this();

? ? ? ? // return this;

? ? }

};

int main3()

{

? ? std::shared_ptr<base> sp2;

? ? // base *sp2;

? ? {

? ? ? ? std::shared_ptr<base> sp1 = make_shared<base>();

? ? ? ? // base b; base *sp1 = &b;

? ? ? ? sp2 = sp1->share_more();

? ? ? ? std::strncpy(sp1->val, "hello", 1024 - 1);

? ? }

? ? cout << "sp2->val == " << sp2->val << endl;

? ? return 0;

}