Rust quick reference

The smallest Rust program: fn main() and the println! macro.

let and let mut, the number types, String and &str, constants, shadowing, and parsing text into numbers.

if as an expression, match, and the three loops: for over a range or iterator, while, and loop with break value.

Define functions with fn, typed parameters and return values, tuples, and closures.

Each value has one owner; pass & to lend it, &mut to let a function change it, and .clone() to copy it.

Vec, slices, HashMap with the entry API, sorting, and iterator chains with filter, map and collect.

Define data with struct and enum, add methods in impl, share behaviour with traits, and derive Debug.

Values that may be missing (Option) and operations that may fail (Result), handled with match, if let, unwrap_or and ?.

String and &str, common methods, formatting, characters vs bytes, and splitting text.

Read what you type in the IDE's Input tab with read_line or lines().

Read project files with fs::read_to_string, return io::Result from main, and write temporary files under /tmp.

Split a program into files with mod, make items visible with pub, and what is available without crates.

What Run compiles, the time limit, input, tests, and what a run cannot do.

Compiler errors such as E0382 use of moved value, E0502, E0308 mismatched types, and panics such as index out of bounds and unwrap on None.

Where to read more: the Rust book, Rust by Example, the standard library and the error index.