Comparison & Ordering (PartialEq, Ord)

Comparison in Rust is powered by four traits — PartialEq and Eq give you == , while PartialOrd and Ord give you and the ability to sort.

Learn Comparison & Ordering (PartialEq, Ord) in our free Rust course — a beginner-friendly interactive lesson with worked examples, a practice exercise and a…

Part of the free Rust course at LearnCodingFast — hands-on lessons with examples you run in your browser, plus practice exercises and a quick quiz.

In this lesson you'll derive these traits, sort with sort , sort_by , and sort_by_key , use cmp and Ordering , find min / max , and see why floats are only PartialOrd .

What You'll Learn in This Lesson

1️⃣ Deriving the Comparison Traits

You rarely write comparison logic by hand. A #[derive(...)] attribute tells the compiler to generate it: PartialEq / Eq for == , and PartialOrd / Ord for , , and friends. Derived ordering compares fields in declaration order .

Because major is declared before minor , two versions are first compared by major ; only when those tie does minor break the tie — exactly how version numbers should sort.

2️⃣ Sorting: sort, sort_by, sort_by_key

Once a type is Ord , sort() orders a slice ascending in place. For custom orders, sort_by takes a comparator closure, and sort_by_key sorts by a key you extract from each element. Iterators also offer min and max .

3️⃣ cmp, Ordering & the Float Catch

The cmp method returns an Ordering — one of Less , Equal , or Greater — which you can match on. Floats only implement the Partial traits, so they use partial_cmp , which returns an Option<Ordering> because NaN is unordered.

Your turn. Fill in the blanks marked ___ , then run it.

Sort a list of players by score, highest first, and print a ranked list. Run it with cargo run and check the output.

📋 Quick Reference — Comparison & Ordering

Practice quiz

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