Rust

Reference

A reference points to the memory of another value. A reference means you borrow the value, but you don’t own it.

let my_number = 8;
let single_reference = &my_number;
let double_reference = &single_reference;

println!(single_reference); // 8
println!(double_reference); // 8

This means that single_reference is only looking at the data of my_number; my_number still owns its data.

Strings

A &str is a simple string. It's just a pointer to the data plus the length. It is also called a string slice.

let my_variable = "Hello, world!";

A String is a pointer with data on the heap.

Ways to make a string:

let my_string = String::from("Hello, World!");
let my_string = "Hello, World!".to_string();
let my_string: String = "Hello, World!".into();

let name = "Bill";
let my_string = format!("Hello, {name}!");

let size_of_string = std::mem::size_of::<String>(); // 24