Vectors

Last reviewed May 28, 2026 Content v20260528

Track mode: server_compiled
Means: Compiled runner
Reading: ~1 min
Level: intermediate

This lesson

This lesson teaches Vectors: the syntax, APIs, and habits you need before advancing in Rust.

Teams ship Vectors on every Rust codebase—skipping it leaves gaps in debugging and code reviews.

You will apply Vectors in contexts like: Infrastructure CLIs, proxies, game engines, blockchain nodes, and latency-sensitive backends.

Write Rust with fn main(), click Run on server—the dev runner compiles main.rs with rustc and runs the binary; fix borrow errors from stderr (requires Rust toolchain; LEARNING_RUNNER_ENABLED=true).

When you can explain the previous lesson's ideas without copying starter code.

Vec<T> is a growable array on the heap. Use push, indexing, and iteration—mind bounds and ownership when moving elements out.

Common operations

let mut v = vec![1, 2, 3];
v.push(4);
let third = v[2];

Important interview questions and answers

Q: Vec vs array?
A: Arrays fixed size on stack; Vec grows on heap with capacity management.

Self-check

What macro creates a vector literal?
What happens on out-of-bounds index?

Interview tip Lesson completion confidence

Can you explain this lesson in 30 seconds without reading notes?

Self-reflection (saved on this device)

Not saved yet.

Playground

Runs on the configured server runner (dev: npm run runner with LEARNING_RUNNER_ENABLED=true). Output appears below the editor.

Code runner not available

Server runner is disabled. Set LEARNING_RUNNER_ENABLED=true and LEARNING_RUNNER_URL in .env (see .env.example).

Check yourself

Multiple choice — immediate feedback.

Discussion

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Starter discussion topics

push vs append?
Capacity reserve?

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