count ← count + 1
IF(count = 10)
{
  DISPLAY(count)
}

REPEAT 5 TIMES
{
  <block>
}

REPEAT UNTIL(x ≥ 10)
{
  <block>
}

scores ← [12, 8, 21]
DISPLAY(scores[1])
DISPLAY(LENGTH(scores))
copy ← scores

PROCEDURE area(w, h)
{
  RETURN(w * h)
}

kitchen ← area(3, 4)

'F' → Fullscreen

How to Use This

Do it once, timed, on paper, in one sitting. A practice paper you dip into over three evenings with a computer open tells you nothing you did not already know.

• Print it or copy the answers onto a sheet. Writing them down is the point — the real paper is written on.
• 36 minutes on Section I, then move, whether or not you have finished. Section II is 26 points and it is the half people under-plan for.
• Reference sheet allowed. Nothing else. No notes, no code, no computer, no looking anything up.
• Mark your own working, not just your answers. A question you guessed right is a question you got wrong.

This is revision, not homework. It is not collected and it is not graded. It also predicts your exam score better than anything else on this site.

Section I — Multiple Choice

22 questions, 2 points each, 44 points, 36 minutes. Pick one answer per question.

1.

In exam notation, which line stores 7 in total?

• (A) total = 7
• (B) total ← 7
• (C) 7 ← total
• (D) IF(total = 7)

2.

In Lua, which operator asks whether two values are equal?

• (A) =
• (B) ==
• (C) ←
• (D) =>

3.

The exam writes a ≥ b. Lua writes the same test as:

• (A) a => b
• (B) a >= b
• (C) a > = b
• (D) a greater b

4.

19 / 4 evaluates to:

• (A) 4
• (B) 4.75
• (C) 3
• (D) 5

5.

19 MOD 4 evaluates to:

• (A) 4
• (B) 4.75
• (C) 3
• (D) 0

6.

10 - 2 * 3 evaluates to:

• (A) 24
• (B) 4
• (C) 6
• (D) 30

7.

In Lua, print("A") followed by print("B") produces:

• (A) A B on one line
• (B) AB on one line
• (C) A and B on separate lines
• (D) An error; print may be called only once

8.

RANDOM(2, 5) can return how many different values?

• (A) 3
• (B) 4
• (C) 5
• (D) Infinitely many, because the result is a decimal

9.

In Lua, print("Score: " .. 7) displays:

• (A) Score: 7
• (B) Score: "7"
• (C) Score:7
• (D) An error; text and numbers cannot be joined

10.

A student types 20 at a local n = io.read() prompt. The next line is if n > 15 then. Which line, added in between, makes that comparison work?

• (A) n = tostring(n)
• (B) n = tonumber(n)
• (C) n = "" .. n
• (D) None; it already works

11.

In Lua, local xs = {1, 2} followed by print(xs[3] + 1) produces:

• (A) 1
• (B) 3
• (C) nil
• (D) The program stops with an error

12.

tonumber("3 apples") returns:

• (A) 3
• (B) 0
• (C) nil
• (D) An error

13.

local t = {10, 20, 30}. The values of t[3] and #t are:

• (A) 30 and 3
• (B) 20 and 3
• (C) 30 and 2
• (D) nil and 3

14.

On the exam reference sheet, APPEND(aList, value):

• (A) Puts value at index 1 and shifts everything right
• (B) Puts value at the end and increases the length by 1
• (C) Replaces the last element with value
• (D) Returns a new list and leaves aList alone

15.

After this runs, nums[1] and LENGTH(nums) are:

nums ← [4, 5, 6]
REMOVE(nums, 1)

• (A) 4 and 3
• (B) 5 and 2
• (C) 4 and 2
• (D) 6 and 2

16.

After this runs, nums[1] and #nums are:

local nums = {4, 5, 6}
table.remove(nums, 1)

• (A) 4 and 3
• (B) 5 and 2
• (C) nil and 2
• (D) 6 and 3

17.

REPEAT 4 TIMES runs its body four times and:

• (A) Gives you a counter variable called i
• (B) Gives you a counter variable you name in the header
• (C) Gives you no counter at all
• (D) Gives you a counter only if the body asks for one

18.

After this runs, count is:

x ← 1
count ← 0
REPEAT UNTIL(x > 6)
{
  x ← x + 2
  count ← count + 1
}

• (A) 2
• (B) 3
• (C) 4
• (D) 6

19.

This displays:

local i = 10

repeat
    i = i + 1
until i > 5

print(i)

• (A) 6
• (B) 10
• (C) 11
• (D) Nothing; the loop never ends

20.

This displays:

a ← [1, 2, 3]
b ← a
b[1] ← 99
DISPLAY(a[1])

• (A) 1
• (B) 99
• (C) 3
• (D) An error; a list cannot be assigned to a list

21.

This displays:

local a = {1, 2, 3}
local b = a
b[1] = 99
print(a[1])

• (A) 1
• (B) 99
• (C) 3
• (D) nil

22.

The Create Performance Task requires at least one student-developed procedure. Which of these counts?

• (A) love.update(dt), because you filled it in
• (B) math.random(1, 6), because you chose the arguments
• (C) rollDice(sides), which you wrote and call yourself
• (D) love.graphics.circle, because it is in your program

Section II — Written Response

Three questions, 26 points, 19 minutes. Write in full sentences where the question asks you to explain something.

23. (8 points) — Tracing a nested loop

count ← 0
i ← 1

REPEAT 3 TIMES
{
  j ← 1
  REPEAT 4 TIMES
  {
    count ← count + 1
    j ← j + 1
  }
  i ← i + 1
}
DISPLAY(count)

(a) How many times does the line count ← count + 1 run? (2 points)

(b) What does the program display? (2 points)

(c) Change exactly one number so that the display is 20, and explain why your change has that effect. (4 points)

24. (8 points) — Finding a run-time error

local scores = {88, 92, 75}
local total = 0

for i = 1, #scores + 1 do
    total = total + scores[i]
end

print(total)

(a) This program stops with an error. Explain what goes wrong and which value causes it. (4 points)

(b) Describe a change that removes the error without deleting the loop, and say what the program then prints. (4 points)

25. (10 points) — Describing an algorithm

A list called temps holds any number of whole numbers.

In detailed steps, describe an algorithm that finds the largest number in the list and displays it. Write it so that somebody else could turn your description into working code without asking you a question.

You may write it in prose, in exam notation, or in Lua. Whichever you choose, your answer must make clear:

• what holds the largest value found so far, and what it starts at
• how you visit every element of the list
• what the comparison is, and what happens when it is true
• when the answer is displayed

After You Have Sat It

Work Through the Section Summaries

One per part of the quarter. Each one has the ideas, the traps, and the exam notation for its sessions — go to the one covering whatever you got wrong:

• Getting Started — sessions 1–6
• Motion and Decisions — sessions 7–14
• Loops and Tables — sessions 15–20
• Functions — sessions 21–23

The Checklist

Everything below is fair game. Tick what you can do without looking:

On the Day

• Documentation sheet in your hand at the door. Not on a computer
• Bring something to write with, and something to write with when that runs out
• The reference sheet is provided. Nothing else
• 36 minutes on Section I, then move — the written section is 26 points

Submit

Nothing. This paper is not collected and it is not graded. Hand in the documentation sheet at the start of the exam period; that one is graded, and it is due on paper.

Quarter Complete