Smart Pointers 1. For each of the following parts, write a single C++ statement

Question

Smart Pointers 1. For each of the following parts, write a single C++ statement that performs the indicated task or write the output that is produced and n only). For each part, assume that all previous statements have been executed (e.g, when doing part e, assume the statements you wrote for parts a throughd have been executed) a. Create a shared pointer name sp1 and set it equal to a dynamically created cs30 objec b. Create a shared pointer sp2 that is created from sp1 c. Using sp1 set the section d. Using sp2 set the numstudents e. Create a shared pointer sp3 f. Point sp3 to what sp1 points to g. Reference count is_ h. Create a weak pointer w1 initialized to sp1 i. Print section using w1 j. Print numstudents using sp1 k. Create a unique pointer name up1 and set it equal to a dynamically created cs30 object 1. Create a unique pointer up2 m. Transfer ownership from up1 to up2 n. Reference count is

Explanation / Answer

#include<iostream>

#include<memory>

#include<string>

using namespace std;

struct cs30

{

string section;

int numstudents;

};

using namespace std;

int main()

{

shared_ptr<cs30> sp1(new cs30); //a

shared_ptr<cs30> sp2(sp1); //b

cout << "Enter the section : ";

cin >> sp1->section; //c

cout << "Enter the number of students: ";

cin >> sp2->numstudents; //d

{

shared_ptr<cs30> sp3; //e

sp3 = sp1; //f

cout << "reference count: " << sp1.use_count()<<endl; //g

}

weak_ptr<cs30> w1=sp1 ; //h

cout << "Section " << w1.lock().get()->section << endl; //i  

cout << "Section " << w1.lock().get()->numstudents << endl;//j

unique_ptr<cs30> up1(new cs30); //k

unique_ptr<cs30> up2; //l

up2 = move(up1); //m

cout << "Reference count is " << sp1.use_count() << endl; //n

}

-----------------------

//output

Enter the section : D

Enter the number of students: 40

reference count: 3

Section D

Section 40

Reference count is 2

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