// ./src/hello/print/fmt.md use std::fmt::{self, Formatter, Display}; struct City { name: &'static str, // Latitude lat: f32, // Longitude lon: f32, } impl Display for City { // `f` is a buffer, and this method must write the formatted string into it fn fmt(&self, f: &mut Formatter) -> fmt::Result { let lat_c = if self.lat >= 0.0 { 'N' } else { 'S' }; let lon_c = if self.lon >= 0.0 { 'E' } else { 'W' }; // `write!` is like `format!`, but it will write the formatted string // into a buffer (the first argument) write!(f, "{}: {:.3}°{} {:.3}°{}", self.name, self.lat.abs(), lat_c, self.lon.abs(), lon_c) } } #[derive(Debug)] struct Color { red: u8, green: u8, blue: u8, } fn part0() { for city in [ City { name: "Dublin", lat: 53.347778, lon: -6.259722 }, City { name: "Oslo", lat: 59.95, lon: 10.75 }, City { name: "Vancouver", lat: 49.25, lon: -123.1 }, ].iter() { println!("{}", *city); } for color in [ Color { red: 128, green: 255, blue: 90 }, Color { red: 0, green: 3, blue: 254 }, Color { red: 0, green: 0, blue: 0 }, ].iter() { // Switch this to use {} once you've added an implementation // for fmt::Display. println!("{:?}", *color); } } pub fn main() { part0(); }