Mastering Rust Functions: A Beginner’s Guide to Efficient Code

In this lesson, we will dive into Rust functions, including syntax, closures, higher-order functions, and best practices for writing efficient, clean, and reusable code.

At this point, we are already somewhat familiar with functions. Since we need to use the main function, which is the entry point of a Rust program, and we have seen a couple of examples in previous lessons, we understand how a function in Rust looks. However, in this lesson, we are going to learn the ins and outs of functions.

Functions

fn say_hello() {
    println!("Hello, world!");
}

fn main() {
    say_hello();
}

// Hello, world!

We define a function in Rust using the keyword fn, followed by the name of the function. Like variables, the function name follows the same convention: it should be in snake_case, such as say_hello in the example above.

fn say_hello(name: &str) {
    println!("Hello, {}!", name);
}

fn main() {
    say_hello("John");
}

// Hello, John!

If we want to pass data to a function, we can do so using function arguments. These need to be specified in parentheses () along with their data types. If a function…