C++ 11 Quizz

 Predict the output of the below set of programs

[1] 
#include <iostream>
#include<memory>
void foo(std::shared_ptr<int> i)
{
    (*i)++;
}
int main ()
{
    auto ptr = std::make_shared<int>(23);
    foo(ptr);
    cout<<*ptr<<endl;
    return 0;
}

[2] Can you change the baove program now using unique_ptr ?

[3]
#include <iostream>
#include<memory>
void foo(std::unique_ptr<int> i)
{
    (*i)++;
}
int main ()
{
    auto ptr = std::make_unique<int>(23);
    foo(ptr);
    cout<<*ptr<<endl;
    return 0;
}

[4] 
void foo(std::unique_ptr<int> i)
{
    (*i)++;
    cout<<" i am in foo() function"<<endl;
    cout<<*i<<endl;
}
int main ()
{
    auto ptr = std::make_unique<int>(23);
    foo(std::move(ptr));
    cout<<"After move ptr = "<<*ptr<<endl;
    return 0;
}

output:
i am in foo() function
24
Segmentation fault

Note: Above program will be crashed as we are trying to access ptr which become NULL after moving it.


#include<iostream>
#include<map> 
#include<memory>
using namespace std;
void foo(std::unique_ptr<int> &i)
{
    (*i)++;
    cout<<" i am in foo() function"<<endl;
    cout<<*i<<endl;
}
int main ()
{
    auto ptr = std::make_unique<int>(23);
    foo(std::move(ptr));
    cout<<"After move ptr = "<<*ptr<<endl;
    return 0;
}

output :
compilation error
cannot bind non-const lvalue reference of type 'std::unique_ptr<int>&' to an rvalue of type 'std::remove_reference<std::unique_ptr<int>&>::type' {aka 'std::unique_ptr<int>'}




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