Creating an array of a set size

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Quick Questions

Shade in the A or B circle for each question.

1. Which line creates an array of 10 elements that all start at 0?

A scores = [0] * 10

B scores = [10] * 0

2. What does names = [''] * 5 create?

A An array of 5 zeros

B An array of 5 empty strings

3. How many elements does marks = [0] * 30 have?

A 1

B 30

4. Which version uses a constant for the array size?

A SIZE = 8 scores = [0] * SIZE

B scores = [0] * size()

5. After scores = [0] * 5, what does scores[2] = 17 do?

A Fills the third element with 17 and leaves the others at 0

B Adds 17 to the end and makes the array 6 elements long

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1scores = [0] * 10		AThe * is inside the brackets, so it makes a list with one element (0 * 10 = 0), not 10 elements. It should be [0] * 10.
2names = [''] * 5		BSIZE = 10 scores = [0] * SIZE
3Use a constant for the size so the array length can be changed in one place		Cscores[2] = 85
4Fill an element of a set-size array by its index		DUses + instead of . A list cannot be added to a number, so this causes an error. It should be [0] 10 to repeat the 0 ten times.
5scores = [0] + 10		ECreates an array of 5 empty strings ready to be filled
6scores = [0 * 10]		FCreates an array of 10 elements, all starting at 0

Definitions

scores = [0] * 10

Fill in the Blanks

Complete each line of code by filling in the missing parts.

scores = [0] _ 10

# Array for 5 student names names = [''] * _

SIZE = 8 marks = [0] * ____

SIZE = 5 scores = [0] * SIZE scores[_] = 75

scores = [0] * 10 for i in range(___(scores)): scores[i] = i * 5

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A scores = [0] x 10

B scores[0] = 85

C scores[1] = 92

D print(len(scores))

Question 2

A SIZE = 5

B names = [] * SIZE

C names[0] = 'Ava'

D print(names)

Question 3

A SIZE = 8

B marks = [0] + SIZE

C for i in range(SIZE):

D marks[i] = i * 10

Question 4

A temps = [0.0] * 7.0

B temps[6] = 31.5

C print(temps)

Question 5

A SIZE = 5

B scores = [0] * SIZE

C scores[5] = 90

D print(scores)

Answer Key

Creating an array of a set size

Section A: Quick Questions

A — scores = [0] * 10

B — An array of 5 empty strings

B — 30

A — SIZE = 8 scores = [0] * SIZE

A — Fills the third element with 17 and leaves the others at 0

Section B: Match the Pairs

scores = [0] * 10 → Creates an array of 10 elements, all starting at 0

names = [''] * 5 → Creates an array of 5 empty strings ready to be filled

Use a constant for the size so the array length can be changed in one place → SIZE = 10 scores = [0] * SIZE

Fill an element of a set-size array by its index → scores[2] = 85

scores = [0] + 10 → Uses + instead of *. A list cannot be added to a number, so this causes an error. It should be [0] * 10 to repeat the 0 ten times.

scores = [0 * 10] → The * is inside the brackets, so it makes a list with one element (0 * 10 = 0), not 10 elements. It should be [0] * 10.

Section C: Definitions

scores = [0] * 10 — Creates a one-dimensional array (list) of 10 elements that all start with the value 0. Change the number to set the size, or use '' for strings.

Section D: Fill in the Blanks

scores = [0] * 10

# Array for 5 student names
names = [''] * 5

SIZE = 8
marks = [0] * SIZE

SIZE = 5
scores = [0] * SIZE
scores[0] = 75

scores = [0] * 10
for i in range(len(scores)):
    scores[i] = i * 5

Section E: Spot the Error

A — x is not a Python operator, so this is a syntax error. Use * to repeat the element: scores = [0] * 10.

B — Repeating an empty list still gives an empty list with 0 elements. Put an empty string inside the brackets: names = [''] * SIZE.

B — You cannot add an integer to a list, so this causes a TypeError. Use * to repeat the starting value: marks = [0] * SIZE.

A — The array size must be a whole number. Multiplying a list by a float causes a TypeError. Use the integer 7.

C — An array of 5 elements has indexes 0 to 4. Index 5 is out of range and causes an IndexError. Use scores[4] = 90 for the last element.