Floats, Booleans, and Chars

fn main() {
    let price: f64 = 19.99;
    let discount: f32 = 0.15;
    println!("price: {}, discount: {}", price, discount);
}

fn main() {
    let is_learning = true;
    let is_finished = false;
    println!("learning: {}, finished: {}", is_learning, is_finished);
}

fn main() {
    let letter = 'R';
    let emoji = '🦀';
    println!("letter: {}, emoji: {}", letter, emoji);
}

fn main() {
    let a: f64 = 0.1 + 0.2;
    let b: f64 = 0.3;
    let close_enough = (a - b).abs() < 1e-10;
    println!("a is close enough to b: {}", close_enough);
}

1. Comparing floating-point numbers with == for exact equality, when tiny rounding errors can make them unequal.
2. Assuming char in Rust is one byte like in C -- a Rust char is actually a 4-byte Unicode scalar value.
3. Forgetting boolean values in Rust are strictly true/false, not 0/1 integers like in some other languages.

• f32 and f64 represent floating-point numbers; f64 is the default and has more precision.
• bool values are exactly true or false and are not interchangeable with integers.
• char represents a single Unicode scalar value, written with single quotes, e.g. a or '🦀'.
• These are all Rust's basic scalar types, alongside integers.