Unit 4: Iteration

What you'll master in this unit

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The three types of loops

Key loop patterns

Counting loop ```java for (int i = 0; i < 10; i++) { System.out.println(i); // prints 0 through 9 } ```

Accumulator loop ```java int sum = 0; for (int i = 1; i <= 100; i++) { sum += i; // sum = 5050 } ```

Sentinel loop ```java while (input != -1) { // process input input = scanner.nextInt(); } ```

String traversal ```java String word = "Hello"; for (int i = 0; i < word.length(); i++) { String ch = word.substring(i, i + 1); System.out.println(ch); } ```

Why Unit 4 matters