Display Trait

Display trait สำหรับ user-facing output formatting

Implementing Display

use std::fmt;

struct Point {
    x: i32,
    y: i32,
}

impl fmt::Display for Point {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "({}, {})", self.x, self.y)
    }
}

struct Temperature {
    celsius: f64,
}

impl fmt::Display for Temperature {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{:.1}°C", self.celsius)
    }
}

fn main() {
    let point = Point { x: 10, y: 20 };
    let temp = Temperature { celsius: 25.5 };

    // print! and println! use Display
    println!("Point: {}", point);
    println!("Temperature: {}", temp);

    // format! uses Display
    let s = format!("Point is {} and temperature is {}", point, temp);
    println!("{}", s);

    // to_string() uses Display
    let point_str = point.to_string();
    println!("As string: {}", point_str);
}