Rust: Ownership and Borrowing

Rust: Ownership and Borrowing
Photo by Mohammad Rahmani / Unsplash

Rust is a unique programming language known for emphasizing safety and performance. One of the key features that sets Rust apart from other languages is its ownership system. In this blog post, we will deeply dive into understanding ownership and borrowing in Rust, especially targeted at intermediate developers looking to strengthen their grasp on these concepts.

Ownership in Rust

In Rust, each value has a variable, which is its owner. The ownership system allows Rust to manage memory without needing a garbage collector. When the owner goes out of scope, the value is dropped, and its memory is freed. This approach helps prevent common issues such as null pointer dereferencing and memory leaks.

Rules of Ownership

  1. Each value in Rust has a single owner.
  2. When the owner goes out of scope, the value is dropped.
  3. Values can be transferred to another owner using "moving."

Borrowing in Rust

While ownership allows Rust to guarantee memory safety, it can also be restrictive at times. Borrowing provides a way to temporarily use a value without taking ownership of it. There are two types of borrowing in Rust:

  1. Immutable Borrowing: Allows multiple references to read the value but not modify it.
  2. Mutable Borrowing: Allows only one reference to write to the value, ensuring data integrity.

Rules of Borrowing

  1. You can have multiple immutable loans or one mutable loan, but not both simultaneously.
  2. The borrow checker enforces these rules simultaneously to prevent data races and ensure thread safety.

Examples and Best Practices

Let's look at a simple example to illustrate ownership and borrowing in Rust:

fn main() {
    let s1 = String::from("Hello");
    let len = calculate_length(&s1);
    println!("Length of '{}' is {}.", s1, len);

fn calculate_length(s: &String) -> usize {

In this example, s1 owns the String value, and calculate_length borrows a reference to it. This way, we can pass values around efficiently without unnecessary copying.

Best Practices

  • Use ownership to manage resources efficiently.
  • I prefer borrowing over cloning for performance reasons.
  • Understand the borrower checker's rules to write safe and efficient code.

By Mastering

Ownership and borrowing are fundamental concepts in Rust that enable memory safety without sacrificing performance. By mastering these concepts, intermediate developers can write robust and efficient code that harnesses the full power of Rust's unique capabilities.

I hope this deep dive into ownership and borrowing in Rust has been insightful for you as an intermediate developer looking to level up your skills in this powerful language. Stay tuned for more advanced topics in future blog posts!

Subscribe to Miguel Norberto

Sign up now to get access to the library of members-only issues.
Jamie Larson