0x30Lesson 4 of 6

Branch and loop over vectors

Use `if`, `match`, loops, and vectors.

15 min 5-question quiz 1 code exercise

By the end of this lesson you can

Process a list of numbers and compute a result.

Rust has familiar control flow (if, else, while, for) plus match for exhaustive branching. Vec<T> is a growable array type. Use iterator patterns and loops to transform and aggregate data clearly.

main.rs

1fn main() {
2    let scores = vec![8, 7, 10];
3    let mut total = 0;
4    for score in scores {
5        total += score;
6    }
7    println!("{}", total);
8}

Output

Rust’s match enforces handling every case, which improves correctness. For loops over vectors are concise and type-safe.

Key takeaways

Process a list of numbers and compute a result.
Rust uses types and ownership rules to prevent common bugs.
Small experiments build intuition quickly.

Lesson quiz

5 questions · pass with 4 correct · up to 50 XP

Passing this quiz completes the lesson and keeps your streak going. Questions you miss come back in review sessions later.

Practice: write Rust

These run for real. Write the program, press Run tests, and read what the compiler tells you - learning to read compiler messages is half of learning C.

Exercise 1

Sum N numbers

+25 XP

Read a count and then that many integers (one per line). Print their sum.

Three values
Negative value

main.rs

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Rust lessons are authored for modern stable Rust; exercises run on Rust 1.82 via Wandbox, a free public service. Your source code and test input are sent to that service.

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