Move Semantics

Move semantics, introduced in C++11, is a major optimization feature that allows resources to be transferred from one object to another instead of being copied. This is particularly important for objects that manage expensive-to-copy resources, such as `std::vector` (which manages a dynamically allocated array) or `std::string`. The mechanism behind move semantics is the **rvalue reference**, denoted by a double ampersand (`&&`). An rvalue reference is a reference that can bind to a temporary object (an rvalue)—an object that is about to be destroyed, like the result of a function call. To enable move semantics, a class can implement a **move constructor** and a **move assignment operator**. These special member functions take an rvalue reference to an object of the same class. Instead of deep-copying the resource, they 'steal' it from the source object and leave the source object in a valid but empty or unspecified state. For example, the move constructor for a `std::vector` wouldn't copy all the elements; it would just copy the pointer to the internal array from the source vector and set the source vector's pointer to `nullptr`. The `std::move` function is used to cast an lvalue (a named object) into an rvalue, signaling that you are done with the object and its resources can be moved from. This avoids unnecessary allocations and copies, significantly improving performance.