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8 lines
1.4 KiB
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<!doctype html><html lang="en"><meta charset="utf-8"><title>Collections and repeated work</title><h1>Collections and repeated work</h1><p>15-minute session: read for 3 minutes, trace for 3, experiment for 7, and complete the check for 2. Spend longer whenever you need.</p><p>A collection stores related values. The loop visits 1, 2, and 3, updating the total from 0 to 1, then 3, then 6. Record this trace rather than guessing. Identify the first and last valid positions in this language: Pascal can declare a 1-based array, while many other examples use zero-based containers. Add another value and update the bounds correctly. Explain what an empty collection should produce.</p><p><code>fn main</code> is the entry point. <code>let</code> introduces a binding; <code>mut</code> permits reassignment. <code>println!</code> is a macro. A reference such as <code>&plan</code> borrows rather than transfers ownership.</p><pre><code class="language-rust">
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fn main() {
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let minutes = [1, 2, 3];
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let mut total = 0;
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for value in minutes { total += value; }
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println!("{}", total);
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}
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</code></pre><p><strong>Expected result:</strong> <code>6</code></p><h3>Practice and evidence</h3><p>Keep three notes: your prediction, the actual result, and why they match or differ. The completion check grades understanding; the practice task builds skill.</p><p><a href="https://doc.rust-lang.org/book/">Language reference</a></p></html> |