Comparison Traits

PartialEq, Eq, PartialOrd, Ord

PartialEq

fn main() {
    // PartialEq - equality comparison (==, !=)
    let a = 42;
    let b = 42;
    let c = 100;

    println!("=== PartialEq ===");
    println!("{} == {}: {}", a, b, a == b);
    println!("{} != {}: {}", a, c, a != c);

    // Strings
    let s1 = String::from("hello");
    let s2 = String::from("hello");
    let s3 = String::from("world");

    println!("\ns1 == s2: {}", s1 == s2);
    println!("s1 == s3: {}", s1 == s3);

    // Can compare different types
    let string = String::from("hello");
    let str_slice = "hello";
    println!("\nString == &str: {}", string == str_slice);

    // NaN is not equal to itself
    let nan = f64::NAN;
    println!("\nNaN == NaN: {}", nan == nan);  // false!
    println!("That's why floats only impl PartialEq, not Eq");
}