Move Semantics and Smart Pointers

1. Introduction to smart pointers and move semantics

In dynamic allocation, the pointer may not be deleted if the function exits early. This can happen via an early return:

#include <iostream>

void someFunction()
{
    Resource* ptr = new Resource();

    int x;
    std::cout << "Enter an integer: ";
    std::cin >> x;

    if (x == 0)
        return; // the function returns early, and ptr won’t be deleted!

    // do stuff with ptr here

    delete ptr;
}

or via a thrown exception:

#include <iostream>

void someFunction()
{
    Resource* ptr = new Resource();

    int x;
    std::cout << "Enter an integer: ";
    std::cin >> x;

    if (x == 0)
        throw 0; // the function returns early, and ptr won’t be deleted!

    // do stuff with ptr here

    delete ptr;
}

One of the best things about classes is that they contain destructors that automatically get executed when an object of the class goes out of scope. A Smart pointer is a composition class that is designed to manage dynamically allocated memory and ensure that memory gets deleted when the smart pointer object goes out of scope.