Pseudocode array to Python list
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. A pseudocode array is declared with DECLARE Scores : ARRAY[1:5] OF INTEGER. Which Python line creates a matching list?
2. In pseudocode, the first element of an array with lower bound 1 is Scores[1]. What is the same element in Python?
3. Which Python statement matches the pseudocode Scores[3] ← 70 (array lower bound 1)?
4. Pseudocode uses Scores[i] inside a loop. How is this written in Python so it works the same way?
5. The pseudocode loop is FOR i ← 1 TO 5. Which Python loop keeps the same i values and reaches every element?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 1scores = [0] * 5 | AThe pseudocode bounds 1 to 5 were copied directly, so scores[i] skips the first element and scores[5] is out of range on the last pass. | |
| 2scores[i - 1] | BA list of 5 elements has indices 0 to 4, so scores[5] is out of range and causes an IndexError. The last element is scores[4]. | |
| 3Pseudocode index 1 is the first element, but the first element of a Python list is at index 0 | CCreates a Python list of 5 elements, all set to 0, to replace the pseudocode array Scores[1:5] | |
| 4A FOR loop from 1 to 5 over a pseudocode array becomes a Python loop over the indices 0 to 4 | DPython's way of writing the pseudocode element Scores[i] when the array starts at index 1 | |
| 5scores = [0] * 5 scores[5] = 90 | Escores[0] | |
| 6for i in range(1, 6): total = total + scores[i] | Ffor i in range(5): |
C
Definitions
scores[i - 1]
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
# ARRAY[1:10] OF INTEGER
scores = [0] * __
2.
# Scores[1] in pseudocode
print(scores[_])
3.
for i in range(1, 6):
print(scores[i - _])
4.
# FOR i = 1 TO 5
for i in range(1, _):
print(scores[i - 1])
5.
for i in range(1, 4):
total = total + scores[i _ 1]
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
scores = [0] * 5
B
for i in range(1, 6):
C
scores[i] = i * 10
D
print(scores)
Question 2
A
marks = [50, 60, 70, 80]
B
first = marks[1]
C
last = marks[3]
D
print(first, last)
Question 3
A
nums = [4, 8, 2, 6, 1, 9]
B
for i in range(1, 6):
C
print(nums[i - 1])
Question 4
A
prices = [0] * 3
B
prices[1] = 2.5
C
prices[1] = 3.0
D
prices[2] = 1.2
E
print(prices)
Question 5
A
scores = [0] * 4
B
for i in range(1, 5):
C
x = int(input())
D
scores[i + 1] = x
E
print(scores)
Answer Key
Pseudocode array to Python list
Section A: Quick Questions
Q1
B — scores = [0] * 5
Q2
A — scores[0]
Q3
A — scores[2] = 70
Q4
B — scores[i - 1]
Q5
A — for i in range(1, 6):
Section B: Match the Pairs
Q1
scores = [0] * 5 → Creates a Python list of 5 elements, all set to 0, to replace the pseudocode array Scores[1:5]
Q2
scores[i - 1] → Python's way of writing the pseudocode element Scores[i] when the array starts at index 1
Q3
Pseudocode index 1 is the first element, but the first element of a Python list is at index 0 → scores[0]
Q4
A FOR loop from 1 to 5 over a pseudocode array becomes a Python loop over the indices 0 to 4 → for i in range(5):
Q5
scores = [0] * 5
scores[5] = 90 → A list of 5 elements has indices 0 to 4, so scores[5] is out of range and causes an IndexError. The last element is scores[4].
Q6
for i in range(1, 6):
total = total + scores[i] → The pseudocode bounds 1 to 5 were copied directly, so scores[i] skips the first element and scores[5] is out of range on the last pass.
Section C: Definitions
Q1
scores[i - 1] — A pseudocode array starting at index 1 becomes a Python list starting at 0, so element Scores[i] is written scores[i - 1] in Python.Section D: Fill in the Blanks
Q1
# ARRAY[1:10] OF INTEGER
scores = [0] * 10Q2
# Scores[1] in pseudocode
print(scores[0])Q3
for i in range(1, 6):
print(scores[i - 1])Q4
# FOR i = 1 TO 5
for i in range(1, 6):
print(scores[i - 1])Q5
for i in range(1, 4):
total = total + scores[i - 1]Section E: Spot the Error
Q1
C — Pseudocode index i starts at 1, but Python lists start at 0, so the element is scores[i - 1]. Using scores[i] gives an IndexError when i is 5.
Q2
B — Marks[1] is the first element in pseudocode, which is index 0 in Python. marks[1] is the second element. It should be marks[0].
Q3
B — FOR i <- 1 TO 6 runs six times, but range(1, 6) stops at 5 and misses the last element. It should be range(1, 7).
Q4
B — Prices[1] in pseudocode is the first element, so in Python it is prices[0]. Writing prices[1] puts the value in the wrong place and it gets overwritten on the next line.
Q5
D — To convert a 1-based pseudocode index to a 0-based Python index you subtract 1, not add 1. It should be scores[i - 1].