What is Smart Pointer?

Same as C++ Smart,shared pointers, it allocates memory and deallocates when all references to it goes out of scope. They only point to 1 value. Examples: vec<T>, String.
Smart pointers are implemented using structs.

Examples

Rc<T> (Reference Counted Pointer)

Single-threaded Shared reference-counting pointers.
Rc provides shared ownership of a value of type T, allocated in the heap.
clone(): Invoking clone on Rc produces a new pointer to the same allocation in the heap. When the last Rc pointer to a given allocation is destroyed, the value stored in that allocation (often referred to as “inner value”) is also dropped

use std::rc::Rc;
struct Person {
    name: String,
    age: u8,
}
fn main() {
    let person = Rc::new(Person {
        name: String::from("Alice"),
        age: 25,
    });

    println!("Name: {}", person.name);              //Alice
    println!("Age: {}", person.age);                //25

    let person_clone1 = person.clone();
    let person_clone2 = person.clone();

    println!("Number of owners: {}", Rc::strong_count(&person));

    drop(person_clone2);
    println!("Number of owners: {}", Rc::strong_count(&person));

    drop(person_clone1);
    println!("Number of owners: {}", Rc::strong_count(&person));
}                
            

Features

1. Mutable Reference

2. Thread Safe (No)