Reading a value from an array element
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. Marks[3] ← 70 and then OUTPUT Marks[3]. What is displayed?
2. Which line READS a value from an array element?
3. Marks[1] is 40 and Marks[2] is 55. What is Total after Total ← Marks[1] + Marks[2]?
4. Score ← Marks[2] has just run. Which statement is true?
5. Marks[4] is 60. After OUTPUT Marks[4], what is stored in Marks[4]?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 1OUTPUT StudentNames[1] | ABest ← Scores[3] | |
| 2Total ← Marks[1] + Marks[2] | BCopy ← Marks[2] OUTPUT Marks[2] | |
| 3Copying one element into a variable: the value is read from the array and stored in the variable | CReads the values in elements 1 and 2 of Marks, adds them and stores the result in Total | |
| 4Reading an element does not change it: the element keeps its value after being used | DThe assignment is the wrong way round. This writes Total into the array element instead of reading the element. To read it, write Total ← Marks[1]. | |
| 5OUTPUT StudentNames(1) | ERound brackets are used instead of square brackets. An array element must be read as StudentNames[1]. | |
| 6Marks[1] ← Total | FDisplays the value stored in element 1 of the StudentNames array |
C
Definitions
OUTPUT StudentNames[1]
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
OUTPUT ____________[1]
2.
OUTPUT StudentNames[_]
3.
Total ← Marks[1] _ Marks[2]
4.
Score ← _____[3]
5.
Best ← Marks[2]
OUTPUT Best
OUTPUT Marks[_]
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
Marks[1] ← 40
B
Marks[2] ← 55
C
Total ← Marks[1] + Marks[2]
D
OUTPUT "Total"
Question 2
A
StudentNames[1] ← "Ava"
B
OUTPUT StudentNames(1)
C
StudentNames[2] ← "Ben"
D
OUTPUT StudentNames[2]
Question 3
A
Score[1] ← 8
B
Score[2] ← 6
C
Copy ← Score[1]
D
OUTPUT Copy[1]
Question 4
A
Quiz[1] = 7
B
Quiz[2] ← 9
C
Total ← Quiz[1] + Quiz[2]
D
OUTPUT Total
Question 5
A
StudentNames[1] ← Zara
B
StudentNames[2] ← "Omar"
C
First ← StudentNames[1]
D
OUTPUT First
Answer Key
Reading a value from an array element
Section A: Quick Questions
Q1
B — 70
Q2
A — OUTPUT StudentNames[1]
Q3
A — 95
Q4
A — Score now holds a copy of the value in Marks[2]
Q5
B — 60
Section B: Match the Pairs
Q1
OUTPUT StudentNames[1] → Displays the value stored in element 1 of the StudentNames array
Q2
Total ← Marks[1] + Marks[2] → Reads the values in elements 1 and 2 of Marks, adds them and stores the result in Total
Q3
Copying one element into a variable: the value is read from the array and stored in the variable → Best ← Scores[3]
Q4
Reading an element does not change it: the element keeps its value after being used → Copy ← Marks[2]
OUTPUT Marks[2]
Q5
OUTPUT StudentNames(1) → Round brackets are used instead of square brackets. An array element must be read as StudentNames[1].
Q6
Marks[1] ← Total → The assignment is the wrong way round. This writes Total into the array element instead of reading the element. To read it, write Total ← Marks[1].
Section C: Definitions
Q1
OUTPUT StudentNames[1] — Reading an element: Name[index] in OUTPUT or an expression gives the value stored in that element. Reading only uses the value, so the element stays unchanged.Section D: Fill in the Blanks
Q1
OUTPUT StudentNames[1]Q2
OUTPUT StudentNames[1]Q3
Total ← Marks[1] + Marks[2]Q4
Score ← Marks[3]Q5
Best ← Marks[2]
OUTPUT Best
OUTPUT Marks[2]Section E: Spot the Error
Q1
D — Quotes make OUTPUT print the word Total instead of the value stored in the variable. It should be OUTPUT Total, which displays 95.
Q2
B — An element is read using square brackets around the index, not round brackets. It should be OUTPUT StudentNames[1].
Q3
D — Copy is an ordinary variable that holds one copied value, not an array, so it has no index. It should be OUTPUT Copy.
Q4
A — A value is stored with the assignment arrow ←, not =. Without it, Quiz[1] never holds 7, so the later reads give the wrong total. It should be Quiz[1] ← 7.
Q5
A — Text must be in quotes. Without them Zara is treated as a variable, so the element would not hold the string read later. It should be StudentNames[1] ← "Zara".