S4 ICT: Python Dictionaries And File Handling (Paper 4 (error Clinic))

S4 ICT: Python Dictionaries and File Handling (Paper 4 (error clinic))

2026-11-14

Tutor Prep Guide · Dictionary key lookup and the get default, membership tests, update and counting, reading a file line by line with strip, word frequency statistics, number conversion and averages, plus the mistakes students repeat most often

S4 ICT: Python Dictionaries and File Handling (Paper 4 (error clinic))

Paper 4 (error clinic): ten questions on Python dictionaries and file reading, with answers and notes.

Direct answers　Level: S4 ICT; format: key lookup, get default, update and counting, line by line file reading, word frequency, number conversion.

01　Paper details (check answers afterwards)

Item	Detail
Questions	10
Suggested time	20
Difficulty mix	Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1
Chapter	Chapter: S4 ICT: Python Dictionaries and File Handling
Level	S4

02　Questions (10 items)

FoundationKey c is missing; how do you avoid the error when reading d[‘c’]?
FoundationA file line reads 12 plus a newline; what happens with a direct int() call?
FoundationWhat is the safest way to avoid forgetting close after opening a file?
IntermediateWhat is the value of the dictionary {1: ‘a’, 1: ‘b’}?
IntermediateWhat goes wrong if you use the assignment sign = for comparison?
IntermediateWhat is the difference between read() and readlines()?
ChallengeWhen counting with d[w] = d[w] + 1, what happens the first time a new word appears?
ChallengeWhat do you get by adding the two strings 10 and 20 directly?
ChallengeWhat is the result of the string comparison ’10’ < ‘9’?
Error redoWhich error appears when the file path is wrong?

03　Answers and one-line notes

#	Answer	One-line note
1	Use d.get(‘c’, default)	get returns a default for a missing key; testing with in is the other safe option.
2	It raises ValueError	int cannot parse the stray newline, so strip the line before converting.
3	Use with open(…) as f	The with block closes the file automatically, even when an exception occurs.
4	‘b’	A repeated key keeps the later value, so it holds b and only one key.
5	Wrong logic or SyntaxError	Comparison needs ==; a single = assigns, so an if condition either fails or is always true.
6	read returns one big string, readlines a list of lines	Use readlines to work line by line and read for the whole text at once.
7	It raises KeyError	The key does not exist yet, so start from get(w, 0) + 1.
8	The string 1020	Adding strings joins them; convert with int first to get 30.
9	True	Strings compare character by character, and 1 is smaller than 9, so True. Convert with int for numeric order.
10	FileNotFoundError	A missing file raises FileNotFoundError; check the path and keep files beside the script for relative paths.

04　What to do after marking

After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
Repeat the same item two days later; move to the next paper only when both attempts are correct.
Parents only need the answer and note columns; there is no need to explain every item.

First ask where the data lives (a dictionary uses keys, a file uses lines), then choose len, get or a counting loop; strip the line ending after reading and convert strings to numbers before any arithmetic.Tutor Registration →

Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.