Cmp Enums

Comparison enums

Ordering

use std::cmp::Ordering;

fn main() {
    // Ordering from comparison
    let result = 5.cmp(&10);
    println!("5 vs 10: {:?}", result);

    let result = 10.cmp(&10);
    println!("10 vs 10: {:?}", result);

    let result = 15.cmp(&10);
    println!("15 vs 10: {:?}", result);

    // Match on ordering
    let a = 42;
    let b = 37;

    match a.cmp(&b) {
        Ordering::Less => println!("{} < {}", a, b),
        Ordering::Equal => println!("{} == {}", a, b),
        Ordering::Greater => println!("{} > {}", a, b),
    }

    // then() for secondary comparison
    #[derive(Debug)]
    struct Person { name: String, age: u32 }

    let people = vec![
        Person { name: "Alice".to_string(), age: 30 },
        Person { name: "Bob".to_string(), age: 25 },
        Person { name: "Alice".to_string(), age: 25 },
    ];

    // Sort by name, then age
    let mut sorted = people;
    sorted.sort_by(|a, b| {
        a.name.cmp(&b.name).then(a.age.cmp(&b.age))
    });

    for p in &sorted {
        println!("{:?}", p);
    }
}