Rust Cheat Sheet

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A searchable, printable Rust reference — ownership and borrowing, traits, pattern matching, Option and Result, iterators and Cargo. Free.

Basics

let x = 5;

Immutable binding (default)

let mut count = 0; count += 1;

Mutable binding

let x = "5"; let x: i32 = x.parse()?;

Shadowing (new type allowed)

i32, u64, f64, bool, char, usize

Core scalar types

let t = (1, "a"); t.0

Tuple + field access

let a = [0u8; 16];

Fixed array of 16 zeros

const MAX_USERS: u32 = 100;

Compile-time constant

let n = big as u8;

Explicit numeric cast

let s: String; let sl: &str;

Owned string vs string slice

println!("{name} has {count}");

Inline variable interpolation

Ownership, borrowing & lifetimes

let b = a; // a is moved

Assignment moves non-Copy types

let b = a.clone();

Deep copy keeps both usable

fn read(s: &String) / read(&s)

Shared borrow (many allowed)

fn edit(s: &mut String) / edit(&mut s)

Exclusive borrow (only one)

// no &mut while & borrows live

The core borrow rule

fn greet(name: &str)

Prefer &str params over &String

i32, bool, char, &T are Copy

Copy types never move

fn first<'a>(a: &'a str, b: &str) -> &'a str

Tie output to an input lifetime

struct View<'a> { text: &'a str }

Struct holding a reference

let s: &'static str = "literal";

Lives for the whole program

Structs, enums & impl

struct User { name: String, age: u32 }

Struct definition

let u = User { name, age: 30 };

Literal + field-init shorthand

let u2 = User { age: 31, ..u };

Struct update syntax

struct Meters(f64);

Tuple struct (newtype idiom)

impl User { fn new(name: String) -> Self { ... } }

Associated constructor

fn label(&self) -> String

Method borrowing self

fn rename(&mut self, n: String)

Method mutating self

enum Shape { Circle(f64), Rect { w: f64, h: f64 } }

Enum with data per variant

#[derive(Debug, Clone, PartialEq)]

Auto-implement common traits

let cfg = Config::default();

Default trait construction

Pattern matching

match n { 0 => "zero", _ => "other" }

Exhaustive match expression

match shape { Shape::Circle(r) => ... }

Destructure enum variants

match n { 1..=5 => "low", _ => "high" }

Range patterns

match p { Point { x, y: 0 } => ... }

Destructure struct fields

Some(n) if n > 10 => "big"

Match guard

id @ 1..=9 => use(id)

Bind while matching (@)

if let Some(v) = opt { use(v); }

Match a single pattern

let Some(v) = opt else { return; };

let-else early exit

while let Some(x) = stack.pop() { ... }

Loop while a pattern holds

matches!(status, Status::Active)

Boolean pattern test macro

Option & Result

let opt: Option<i32> = Some(5);

Maybe-a-value type

let res: Result<T, E> = Ok(v);

Success-or-error type

let v = load()?;

? propagates None / Err up

opt.unwrap_or(0)

Value or a default

opt.unwrap_or_else(|| compute())

Lazy default

opt.unwrap_or_default()

Value or Default::default()

opt.map(|v| v * 2)

Transform if present

opt.and_then(|v| v.checked_mul(2))

Chain fallible steps (flatMap)

opt.ok_or(MyError::Missing)?

Option → Result

res.map_err(|e| AppError::Io(e))

Convert the error type

opt.is_some(); res.is_err();

Cheap state checks

let v = opt.take();

Move out, leave None behind

Traits & generics

trait Greet { fn hello(&self) -> String; }

Trait: shared behavior

trait Greet { fn wave(&self) { ... } }

Default method body

impl Greet for User { ... }

Implement for a type

fn welcome<T: Greet>(x: &T)

Generic with a trait bound

fn f<T>(x: T) where T: Greet + Clone

where clause for many bounds

fn welcome(x: &impl Greet)

impl Trait argument sugar

fn make() -> impl Iterator<Item = u32>

Opaque return type

let objs: Vec<Box<dyn Greet>> = ...;

Trait objects (dynamic dispatch)

impl From<u32> for Meters { ... }

From gives you Into for free

let m: Meters = 5u32.into();

Convert via Into

impl fmt::Display for User { ... }

Custom {} formatting

Collections

let mut v = vec![1, 2, 3];

Vec literal macro

v.push(4); v.pop();

Append / remove last

v.get(0) // Option<&T>

Safe indexing (v[9] panics)

for x in &v { ... }

Iterate by reference

v.sort(); v.sort_by_key(|u| u.age);

In-place sorting

v.retain(|x| *x > 0);

Keep matching elements

let mut m = HashMap::new(); m.insert(k, v);

Hash map basics

*counts.entry(word).or_insert(0) += 1;

Entry API counter idiom

m.contains_key(&k); m.get(&k);

Lookups return Option

s.push_str("more"); format!("{a}{b}")

Grow / build strings

s.chars().rev().collect::<String>()

Char-wise string processing

names.join(", ")

Join a Vec<String>

Iterators & closures

v.iter().map(|x| x * 2).collect::<Vec<_>>()

Transform and materialize

.filter(|x| **x > 0)

Keep matching elements

.filter_map(|s| s.parse().ok())

Filter + map in one pass

.sum::<i32>(); .count(); .max()

Common consumers

.fold(0, |acc, x| acc + x)

General reduction

.enumerate()

Pairs of (index, item)

.zip(other.iter())

Walk two iterators together

.take(5); .skip(2); .rev()

Slice and reverse lazily

.flat_map(|l| l.split(' '))

Map then flatten

.any(|x| x < 0); .all(|x| x > 0)

Short-circuit predicates

.find(|u| u.id == id); .position(...)

First match / its index

iter() &T; iter_mut() &mut T; into_iter() T

The three iteration modes

let add = move |x| x + base;

move closure takes ownership

.collect::<HashMap<_, _>>()

Collect pairs into a map

Error handling

fn run() -> Result<(), Box<dyn Error>>

Quick catch-all error type

fn main() -> anyhow::Result<()>

anyhow for applications

file.read().context("reading config")?;

anyhow: attach context

anyhow::bail!("invalid input: {x}");

Early return with an error

#[derive(thiserror::Error, Debug)]

thiserror for libraries

#[error("user {0} not found")] NotFound(u64),

Display message per variant

#[error(transparent)] Io(#[from] std::io::Error),

Auto-From wrapped errors

enum AppError { Db(String), Timeout }

Custom error enum

let n = do_it()?; // Err auto-converts

? uses From between error types

opt.expect("config must be loaded")

unwrap/expect: tests only

eprintln!("error: {e:#}");

Print the full error chain

Smart pointers & interior mutability

let b = Box::new(BigStruct::new());

Heap allocation, sole owner

enum List { Node(i32, Box<List>), Nil }

Box enables recursive types

let a = Rc::new(data); let b = Rc::clone(&a);

Shared owner, single thread

let a = Arc::new(data);

Shared owner across threads

let c = RefCell::new(0); *c.borrow_mut() += 1;

Runtime-checked mutation

Rc<RefCell<T>>

Shared + mutable (one thread)

let m = Mutex::new(0); *m.lock().unwrap() += 1;

Thread-safe mutation

Arc<Mutex<T>>

Shared + mutable across threads

let l = RwLock::new(map); l.read(); l.write();

Many readers or one writer

Cell::new(5).set(6);

Copy-type interior mutability

let w = Rc::downgrade(&a); w.upgrade()

Weak breaks reference cycles

Concurrency & async

let h = thread::spawn(|| work()); h.join()

Spawn and join a thread

thread::spawn(move || use(data))

move data into the thread

thread::scope(|s| { s.spawn(|| ...); })

Borrow locals in threads

let (tx, rx) = mpsc::channel();

Multi-producer channel

tx.send(job)?; let job = rx.recv()?;

Send / blocking receive

let n = Arc::new(Mutex::new(0));

Shared counter pattern

#[tokio::main] async fn main() { ... }

Async runtime entry point

async fn fetch() -> Result<Data>

Async function

let data = fetch().await?;

Await a future

let h = tokio::spawn(fetch()); h.await??;

Spawn an async task

let (a, b) = tokio::join!(f1(), f2());

Run futures concurrently

tokio::time::sleep(Duration::from_secs(1)).await;

Non-blocking sleep

tokio::select! { r = f1() => ..., _ = f2() => ... }

First future to finish wins

Cargo CLI

cargo new my-app

Create a binary project

cargo add serde --features derive

Add a dependency

cargo run

Build and run (debug)

cargo build --release

Optimized build

cargo check

Type-check fast, no binary

cargo test

Run tests (+ doc tests)

cargo clippy -- -D warnings

Lints, warnings as errors

cargo fmt

Format the whole project

cargo doc --open

Build and browse the docs

cargo update

Refresh Cargo.lock versions

cargo install ripgrep

Install a binary crate

cargo tree

Show the dependency graph

No entry matches “:q”.

About Rust Cheat Sheet

This Rust cheat sheet maps the language by concept on one searchable page: basics, ownership, borrowing and lifetimes, structs, enums and impl blocks, pattern matching, Option and Result, traits and generics, collections, iterators and closures, error handling, smart pointers and interior mutability, concurrency and async, and the Cargo command line.

Ownership is the part of Rust people come back to look up, so it gets its own section next to lifetimes, borrowing rules, Box, Rc, Arc and RefCell — alongside the everyday syntax like match arms, the ? operator, iterator adapters and deriving traits.

Like every cheat sheet in this group it is free and client-side: filter rows live with the search box, hop between sections with the sticky table of contents, copy any snippet with one click and print the page as a desk reference.

How to use Rust Cheat Sheet

Open the sheet and review the sections, from Basics and Ownership & borrowing to the Cargo CLI.
Search for a keyword such as lifetime, match or Arc to filter the sheet live.
Jump to Option & Result or Error handling when you need the idiomatic way to fail.
Click a snippet or its copy icon to copy the Rust code to your clipboard.
Use Print for a paper copy of the full Rust reference.

Frequently asked questions

Twelve sections: basics, ownership, borrowing and lifetimes, structs, enums and impl, pattern matching, Option and Result, traits and generics, collections, iterators and closures, error handling, smart pointers and interior mutability, concurrency and async, and the Cargo CLI.

Yes. A dedicated section shows moves, borrows, mutable borrows, the borrow-checker rules and lifetime annotations with short explanations on each row.

It does — Option and Result combinators, the ? operator, custom error types, From conversions and the common crate patterns each appear as copy-ready snippets.

Yes. Click the code on any row or its copy icon and it is copied immediately.

Yes, it is completely free and runs in your browser with no login.

Rust Cheat Sheet

Basics

Ownership, borrowing & lifetimes

Structs, enums & impl

Pattern matching

Option & Result

Traits & generics

Collections

Iterators & closures

Error handling

Smart pointers & interior mutability

Concurrency & async

Cargo CLI

About Rust Cheat Sheet

How to use Rust Cheat Sheet

Frequently asked questions

What does the Rust cheat sheet cover?

Does it explain ownership and borrowing?

Does it cover error handling?

Can I copy a snippet with one click?

Is the Rust reference free?

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