Test — Module 2: Control Flow¶

Topic: [[go]] Module: [[go/2. Control Flow]]

Before You Begin¶

[!WARNING] Do not look at ANSWERS.md or your notes during the test. The purpose of this test is to surface what you truly know vs. what you think you know. An inflated score is worthless. An honest score shows you exactly where to focus next.

Instructions: 1. Close all notes, the module README, and any reference materials. 2. Set a timer. Note your start time below. 3. Attempt every question — partial credit exists. 4. After finishing, grade yourself using ANSWERS.md. 5. Record your score in the Grading Record at the bottom.

Start time: ___________ End time: ___________ Total time: ___________

Scoring Table¶

Passing score: 15/22 (68%)  ·  Target score: 18/22 (82%)

Section 1: Recall (5 questions × 1 pt = 5 pts)¶

Quick recall questions. Answer from memory in 1–3 sentences each.

1.1 Does Go require parentheses around the condition in an if statement? For example, is if (x > 0) { ... } valid Go?

Your answer:

1.2 How many loop constructs does Go have? Name them all (including any keyword aliases or variants).

Your answer:

1.3 Does Go's switch statement fall through between cases by default? What keyword do you use if you want explicit fall-through behavior?

Your answer:

1.4 When does a deferred function call actually execute — at the defer statement, or at some other time? Be specific.

Your answer:

1.5 What does continue do inside a Go for loop? How does it differ from break?

Your answer:

Section 2: Conceptual Understanding (3 questions × 2 pts = 6 pts)¶

Demonstrate that you understand the "why", not just the "what".

2.1 Explain the "init statement" in a Go if expression. Give a concrete example. Why is this pattern useful, and what is the scope of any variable declared in the init statement?

Your answer:

2.2 Go has no while keyword and no do-while keyword. Explain how you simulate each of these two loop patterns using Go's for loop. Why might the Go designers have made this consolidation intentional rather than accidental?

Your answer:

2.3 Explain the LIFO (last-in, first-out) execution order of deferred calls. Give a concrete scenario — for example, acquiring multiple resources in sequence — to illustrate why this ordering is useful rather than arbitrary.

Your answer:

Section 3: Applied / Practical (2 questions × 3 pts = 6 pts)¶

Show that you can use your knowledge to solve real problems.

3.1 Write a complete Go program that: - Declares the map scores := map[string]int{"Alice": 90, "Bob": 85, "Carol": 92} - Uses for range to iterate over the map and print each name and score (e.g., Alice: 90) - After the loop, computes and prints the average score

Note: map iteration order in Go is not guaranteed — your output order may differ from the expected output, and that is correct.

Your answer:

3.2 Write a Go function classify(n int) string that returns: - "negative" for any n < 0 - "zero" for n == 0 - "small" for 1 <= n <= 9 - "medium" for 10 <= n <= 99 - "large" for n >= 100

Use a switch statement (not if/else if). Show how you would call and test this function with at least 5 different values.

Your answer:

Section 4: Scenario / Debugging (1 question × 3 pts = 3 pts)¶

Analyze a realistic scenario and identify what's wrong or what should be done.

4.1 The following code is supposed to print only the matching case's output — "one" when n is 1, "two" when n is 2, "three" when n is 3. But a programmer who came from C has written it with fallthrough everywhere, which causes unexpected behavior:

switch n {
case 1:
    fmt.Println("one")
    fallthrough
case 2:
    fmt.Println("two")
    fallthrough
case 3:
    fmt.Println("three")
}

Identify:

a) What actually happens when this code runs with n = 2? Trace the execution precisely.

b) Why does this happen? Explain what fallthrough does in Go — specifically, does it check the next case's condition or not?

c) The programmer's underlying goal was probably: "I want to match any of 1, 2, or 3 and do the same thing." Rewrite the switch correctly for that goal, and also rewrite it for the original goal (each number prints its own word).

Your answer:

Section 5: Essay / Discussion (1 question × 2 pts = 2 pts)¶

Open-ended. There is more than one good answer. Show your reasoning.

5.1 "Using defer inside a for loop is a common source of resource leaks in Go." Explain why this statement is true. Describe the pattern that correctly handles per-iteration cleanup, and explain why it works where defer-in-a-loop does not.

Consider at least two perspectives in your answer: what the programmer likely intended vs. what actually happens, and how Go's design of defer (scoped to function return) makes this a natural pitfall.

Your answer (aim for 3–6 sentences):

Section 6: Bonus Challenge (1 question × +5 pts)¶

[!NOTE] This question is optional. It will not count against you if you skip it or get it wrong. Only attempt it after completing Sections 1–5.

6.1 Go's for...range loop over a string iterates over Unicode runes, not bytes. Write a complete Go program that demonstrates this with the string "café" and shows all four of the following:

1. The byte length using len()
2. The rune count using utf8.RuneCountInString()
3. Iteration using range — print each rune's byte index and its Unicode code point value
4. A brief explanation (in a comment or print statement) of why range is safer than byte indexing for Unicode text, based on what your program's output shows

Bonus points for also showing what byte indexing (s[i]) produces vs. rune indexing for the é character specifically.

Your answer:

Self-Assessment¶

After grading your test, answer these questions honestly:

What did I get right and why?

Your reflection:

What did I get wrong and why did I make that mistake?

Your reflection:

What should I review before moving to the next module?

Your reflection:

What score did I get? Do I feel it accurately reflects my understanding?

Your reflection:

Grading Record¶

Append a new row each time you take this test. Do not overwrite previous attempts.

Grade scale: A ≥ 90% (≥20/22)  ·  B ≥ 80% (≥18/22)  ·  C ≥ 70% (≥15/22)  ·  D ≥ 60% (≥13/22)  ·  F < 60%

See ANSWERS.md for the answer key. Review it only after completing the test.