Rust Cheat Sheet

A quick lookup page for things you’ll want to check without re-reading a whole lesson. Each section links back to the page that explains it properly.

Keywords

Keyword	Meaning
`let`	Declare a variable (Variables)
`mut`	Make a variable or reference mutable (Variables)
`const`	Declare a constant (Variables)
`fn`	Declare a function (Functions)
`struct`	Declare a struct (Structs)
`enum`	Declare an enum (Enums)
`impl`	Add methods to a type (Structs, Traits)
`trait`	Declare a trait (Traits)
`match`	Pattern match on a value (Match)
`if let` / `while let`	Match a single pattern (If Let / While Let)
`loop` / `while` / `for`	The three loop types (Loops, While, For)
`break` / `continue`	Control a loop (Break/Continue)
`mod`	Declare a module (Modules)
`pub`	Make an item public outside its module (Modules)
`use`	Bring a path into scope (Modules)
`unsafe`	Unlock raw pointers and other checked-by-you operations (Unsafe)
`move`	Force a closure to take ownership of captured values (Concurrency)
`&` / `&mut`	Borrow / mutably borrow a value (Borrowing)

Method	What it does
`.len()`	Length in bytes
`.trim()`	Removes leading/trailing whitespace
`.to_uppercase()` / `.to_lowercase()`	Case conversion
`.contains(pat)`	Whether a substring/pattern is present
`.replace(from, to)`	Replace all matches
`.push_str(s)`	Append a `&str`
`.push(c)`	Append a single `char`
`.chars()`	Iterate character by character
`.split(pat)`	Split into an iterator of substrings
`.parse::<T>()`	Convert text into another type (returns `Result`)

See the Strings page for details and examples.

Method	What it does
`.push(x)`	Add to the end
`.pop()`	Remove and return the last item (`Option`)
`.remove(i)`	Remove the item at index `i`
`.len()`	Number of items
`.is_empty()`	Whether the vector has no items
`.get(i)`	Safe indexed access (`Option`, doesn’t panic)
`.iter()`	Iterate by reference
`.contains(&x)`	Whether a value is present
`.sort()`	Sort in place

See the Vectors and Iterators pages for details and examples.

Method	Works on	What it does
`.unwrap()`	Both	Get the value, panics if `None`/`Err`
`.expect("msg")`	Both	Like `.unwrap()`, with a custom panic message
`.unwrap_or(default)`	Both	Get the value, or a fallback
`.is_some()` / `.is_none()`	`Option`	Check which variant it is
`.is_ok()` / `.is_err()`	`Result`	Check which variant it is
`?`	Both	Return early on `None`/`Err`

See the Option and Result pages for details and examples.

Specifier	What it prints
`{}`	Normal display (needs the `Display` trait)
`{:?}`	Debug format
`{:#?}`	Pretty-printed debug format
`{:.2}`	2 decimal places
`{:5}`	Pad to a width of 5
`{name}`	Inline a variable named `name`

See the Output page for details and examples.

See the For and Slices pages for details and examples.