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3 lines
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<!doctype html><html lang="en"><meta charset="utf-8"><title>Values and decisions</title><h1>Values and decisions</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 decision chooses which statements run. The policy here is “ready at 80 or higher.” Trace 85, 79, 80, and 81 before running each case. The comparison includes 80. A program that prints the right answer for 85 may still be wrong at the boundary. Add a separate check rejecting scores below 0 or above 100; rejection and needing practice mean different things.</p><p><code>let</code> introduces an immutable binding and <code>var</code> a mutable one. Converting text with <code>Int(raw)</code> may produce <code>nil</code>. <code>if let</code> unwraps a present value without force-unwrapping missing data.</p><pre><code class="language-swift">let score = 85
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if score >= 80 { print("Ready") } else { print("Practice") }
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</code></pre><p><strong>Expected result:</strong> <code>Ready</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://docs.swift.org/swift-book/documentation/the-swift-programming-language/">Language reference</a></p></html> |