christmas_carol.rs

fn main() {
    for i in 1..=12 {
        println!("On the {} day of Christmas", to_ordinal(i));
        println!("My true love sent to me");

        for j in (2..=i).rev() {
            match j {
                12 => println!("12 drummers drumming"),
                11 => println!("Eleven pipers piping"),
                10 => println!("Ten lords a-leaping"),
                9 => println!("Nine ladies dancing"),
                8 => println!("Eight maids a-milking"),
                7 => println!("Seven swans a-swimming"),
                6 => println!("Six geese a-laying"),
                5 => println!("Five golden rings (five golden rings)"),
                4 => println!("Four calling birds"),
                3 => println!("Three French hens"),
                2 => println!("Two turtle-doves"),
                unknown => println!("unknown value: {}", unknown)
            }
        }

        println!("{} partridge in pear tree\n", if i == 1 { "A" } else { "And a" })
    }
    println!("And a partridge in pear tree");
}

fn to_ordinal(n: i32) -> &'static str {
    match n {
        1 => "first",
        2 => "second",
        3 => "third",
        4 => "fourth",
        5 => "fifth",
        6 => "sixth",
        7 => "seventh",
        8 => "eighth",
        9 => "ninth",
        10 => "tenth",
        11 => "11th",
        12 => "12th",
        _more => "unknown"
    }
}

fibonacci.rs

fn main() {
    println!("fib {}", fibonacci(8));
}

fn fibonacci(n: i32) -> i32 {
    if n == 0  {
        return 0
    }

    if n == 1 {
        return 1
    }

    fibonacci(n - 2) + fibonacci(n - 1)
}

temperature.rs

fn main() {
    let celsius = 25.0;
    let fahrenheit = 70.0;

    println!("{}℃ is {}℉", celsius, celsius_to_fahrenheit(celsius));
    println!("{}℉ is {}℃", fahrenheit, fahrenheit_to_celsius(fahrenheit));
}

fn celsius_to_fahrenheit(celsius: f64) -> f64 {
    celsius * 1.8 + 32.0
}

fn fahrenheit_to_celsius(fahrenheit: f64) -> f64 {
    (fahrenheit - 32.0) / 1.8
}