Useful commands for Rust Programming Language

Statements and Expressions

• Statements are instructions that perform some action and do not return a value
• Expressions evaluate to a resultant value

Traditional vs Named Placeholder Syntax

Traditional Placeholder Syntax {} was introduced in Rust 1.0

let apple: i32 = 50;
let banana: i32 = 100;
println!("apple = {}", apple);
println!("banana = {}", banana);

Named Placeholder Syntax {apple} or {banana} was introduced in Rust 1.58.0 (released in January 2022)

let apple: i32 = 50;
let banana: i32 = 100;
println!("apple = {apple}");
println!("banana = {banana}");

Positional Arguments

let apple: i32 = 50;
let banana: i32 = 100;
println!("I have {0} apples and {1} bananas. I can't believe that I have {0} apples", apple, banana);

Keep dead code and suppress the warning

To keep the unused variants and suppress the warning, you can annotate part of your code with

#[allow(dead_code)]

Type Aliases

type Kilometers = i32;

fn main() {
    let half_marathon: Kilometers = 21;
    let full_marathon: Kilometers = 42;
}

Using nested paths to clean up large use lists

use std::cmp::Ordering;
use std::io;

// Combining two use statements that share a subpath
use std::io;
use std::io::Write;

Instead of the multiple lines in the example above, we can use nested paths to bring the same items into scope with one line

use std::{cmp::Ordering, io};

// Combining two use statements that share a subpath
use std::io::{self, Write};