Rust by Example

19.1 Documentation

Doc comments are very useful for big projects that require documentation. When running Rustdoc, these are the comments that get compiled into documentation. They are denoted by a ///, and support Markdown.

#![crate_name = "doc"]

/// A human being is represented here
pub struct Person {
    /// A person must have a name, no matter how much Juliet may hate it
    name: String,

impl Person {
    /// Returns a person with the name given them
    /// # Arguments
    /// * `name` - A string slice that holds the name of the person
    /// # Example
    /// ```
    /// // You can have rust code between fences inside the comments
    /// // If you pass --test to Rustdoc, it will even test it for you!
    /// use doc::Person;
    /// let person = Person::new("name");
    /// ```
    pub fn new(name: &str) -> Person {
        Person {
            name: name.to_string(),

    /// Gives a friendly hello!
    /// Says "Hello, [name]" to the `Person` it is called on.
    pub fn hello(& self) {
        println!("Hello, {}!",;

fn main() {
    let john = Person::new("John");


To run the tests, first build the code as a library, then tell rustdoc where to find the library so it can link it into each doctest program:

rustc --crate-type lib
rustdoc --test --extern doc=""

(When you run cargo test on a library crate, Cargo will automatically generate and run the correct rustc and rustdoc commands.)