9618Paper 2 · Fundamental Problem-solving and Programming Skills§10.1, §10.2, §10.3, §10.4

10. Data Types and Structures

Data types, records, arrays (1D/2D), files, and how ADTs are implemented with arrays.

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Statometer93BankerNext Paper 293%

Marks a paper35.1 · 47%Rank#2 of 12 · #2 on P2Trend · last 12↘Full stats

Everything for this topic — study hub

AS Level · 9618 · Paper 2

This topic is rows 29–32 of the study route.Open it on your study route

Statometer — what 33 real papers say about this topic and each of its 4 syllabus bullets

Banker · #2 of 12 in AS Level · recomputed with every new session

Banker#2 of 12 in AS Level#2 on Paper 2↘ Easing

Set in nearly every paper and worth a big slice of it — revise first, expect it.

Next Paper 2: 93%; 9 in 10 chance it is set
Marks a paper: 35.1 / 75; 47% of Paper 2 · fair share 25%
Appeared in: 32 / 33; Paper 2 sittings 2021–2026
Last set: May/Jun 2026; 9618/23 · Q7 · 9 marks · 11-series streak

Marks in each of the last 12 Paper 2 sittingsOct/Nov 24 → May/Jun 26

What the papers say

Set in 32 of 33 Paper 2 sittings on the current syllabus — treat it as certain.
Worth about 35.1 marks a paper (47% of Paper 2, 1.9× its fair share).
Last set May/Jun 2026 · 9618/23 · Q7 for 9 marks — in the most recent series.
Set in each of the last 11 series without a miss.
Easing off: about 43 marks a paper earlier, 30.8 in the latest years — still examined, just smaller.
Lives on “Write” and “Complete” — 83% of its questions: you must produce something — code, a diagram, a table — practise doing it, not reading it.
53% of its questions involve a diagram, table or figure — practise with pen and paper.
84% of its questions are set out as code, pseudocode or a table to complete.
Most of its marks (66%) come in extended questions of 12+ marks — plan the answer before writing.
Its biggest question so far: 21 marks (May/Jun 2023 · 9618/21 · Q8).
Inside the topic, §10.1 Data types and records carries the most marks (40%) and §10.4 Introduction to abstract data types the least (10%).
It is examined mostly as AO2 (Apply & analyse, 53%), the rest AO3 (47%) — you must apply it to the given data or scenario — work it out, trace it, explain it in context.
The examiner has commented on 138 of its questions — read “What the examiner said” before you practise.

Command words

Share of questions using the word (a question can use several). What each wants →

Question shapes

≤ 6 mk20
7–9 mk31
10–12 mk57
13–15 mk34
16+ mk45

Average 12.3 marks a question · 53% with a figure or table · 84% with code · biggest 21 marks

Assessment objectives — how it is examined

Every part of every current-syllabus question filed under Cambridge's AO1 / AO2 / AO3 (from its command word and what it asks you to do), so you know whether this topic pays for definitions, for applying, or for judging and building.

AO2 53%

AO3 47%

AO1 Knowledge & understanding
AO2 Apply & analyse
AO3 Design, program & evaluate

Paper 2 as a whole

Paper 2	Syllabus	Measured
AO1 Knowledge & understanding	0%	0%
AO2 Apply & analyse	40%	45%
AO3 Design, program & evaluate	60%	55%

Syllabus = Cambridge's grid; measured = the bank's current-syllabus papers.

Inside the topic — every syllabus bullet, measured

Each part of each question is filed under the bullet it examines; the numbers are per Paper 2 sitting, exactly like the topic's. Open a bullet for its own Statometer.

10.1Data types and records#5 of 14 on Paper 2Banker · 9382% next paper9.9 marks30/33 sittings↘ May/Jun 2026Banker · 9382%
9.9 · 40% of topic30/33May/Jun 2026latest series · ↘
Asked in nearly every paper — the bullet to know cold.Syllabus: choosing INTEGER, REAL, CHAR, STRING, BOOLEAN, DATE; defining a record structure and reading from / writing to its fields
Next Paper 2
82%
8 in 10
Marks a paper
9.9
13% of the paper · 40% of the topic
Asked in
30 / 33
Paper 2 sittings · 131 questions
Last asked
May/Jun 2026
9618/21 · Q9 · 5 marks · 11-series streak
Asked in 30 of 33 Paper 2 sittings — nearly every paper.
About 9.9 marks a paper (13% of Paper 2; 40% of the topic's marks across its 4 bullets).
Last asked May/Jun 2026 · 9618/21 · Q9 (5 marks) — in the most recent series.
Asked in each of the last 11 series.
Easing: 15 → 7 marks a paper.
Usually “Write” or “Complete”: you must produce something — code, a diagram, a table — practise doing it, not reading it.
Biggest chunk of marks so far: 14 in May/Jun 2023 · 9618/21 · Q8.
It is examined mostly as AO3 (Design, program & evaluate, 58%), the rest AO2 (42%) — you must build it — write the pseudocode or program, design the structure.
Last 12 sittings↘ Easing
Assessment objectives
AO2 42%
AO3 58%
AO1 Knowledge & understanding
AO2 Apply & analyse
AO3 Design, program & evaluate
Write57%
Complete47%
State34%
Give31%
Practise its 131 questions Biggest: 14 marks · May/Jun 2023
10.2Arrays#4 of 14 on Paper 2Banker · 9484% next paper11.9 marks29/33 sittings→ May/Jun 2026Banker · 9484%
11.9 · 33% of topic29/33May/Jun 2026latest series · →
Asked in nearly every paper — the bullet to know cold.Syllabus: index, upper and lower bounds; choosing a 1D or 2D array; pseudocode for arrays; bubble sort and linear search on an array
Next Paper 2
84%
8 in 10
Marks a paper
11.9
16% of the paper · 33% of the topic
Asked in
29 / 33
Paper 2 sittings · 104 questions
Last asked
May/Jun 2026
9618/23 · Q7 · 8 marks · 11-series streak
Asked in 29 of 33 Paper 2 sittings — nearly every paper.
About 11.9 marks a paper (16% of Paper 2; 33% of the topic's marks across its 4 bullets).
Last asked May/Jun 2026 · 9618/23 · Q7 (8 marks) — in the most recent series.
Asked in each of the last 11 series.
Usually “Write” or “Complete”: you must produce something — code, a diagram, a table — practise doing it, not reading it.
Biggest chunk of marks so far: 16.5 in Oct/Nov 2022 · 9618/22 · Q7.
It is examined mostly as AO3 (Design, program & evaluate, 69%), the rest AO2 (31%) — you must build it — write the pseudocode or program, design the structure.
Last 12 sittings→ Steady
Assessment objectives
AO2 31%
AO3 69%
AO1 Knowledge & understanding
AO2 Apply & analyse
AO3 Design, program & evaluate
Write62%
Complete42%
State28%
Describe27%
Practise its 104 questions Biggest: 16.5 marks · Oct/Nov 2022
10.3Files#8 of 14 on Paper 2Regular · 5460% next paper4.1 marks21/33 sittings↘ May/Jun 2026Regular · 5460%
4.1 · 17% of topic21/33May/Jun 2026latest series · ↘
Set most sessions for a few marks; know the definition and one example.Syllabus: why files are needed; pseudocode to read from and write to text files of one or more lines
Next Paper 2
60%
6 in 10
Marks a paper
4.1
5% of the paper · 17% of the topic
Asked in
21 / 33
Paper 2 sittings · 55 questions
Last asked
May/Jun 2026
9618/22 · Q3 · 6 marks · 11-series streak
Asked in 21 of 33 Paper 2 sittings — about 6 papers in 10.
About 4.1 marks a paper (5% of Paper 2; 17% of the topic's marks across its 4 bullets).
Last asked May/Jun 2026 · 9618/22 · Q3 (6 marks) — in the most recent series.
Asked in each of the last 11 series.
Easing: 5.5 → 3.4 marks a paper.
Usually “Write” or “Complete”: you must produce something — code, a diagram, a table — practise doing it, not reading it.
Biggest chunk of marks so far: 13 in May/Jun 2024 · 9618/22 · Q8.
It is examined mostly as AO2 (Apply & analyse, 52%), the rest AO3 (48%) — you must apply it to the given data or scenario — work it out, trace it, explain it in context.
Last 12 sittings↘ Easing
Assessment objectives
AO2 52%
AO3 48%
AO1 Knowledge & understanding
AO2 Apply & analyse
AO3 Design, program & evaluate
Write66%
Complete40%
Describe38%
State27%
Practise its 55 questions Biggest: 13 marks · May/Jun 2024
10.4Introduction to abstract data types#6 of 14 on Paper 2Core · 6971% next paper5.5 marks24/33 sittings→ May/Jun 2026Core · 6971%
5.5 · 10% of topic24/33May/Jun 2026latest series · →
A regular earner inside the topic — most papers touch it.Syllabus: stacks, queues and linked lists: features, when to use each, adding/editing/deleting data, and how each is implemented with arrays
Next Paper 2
71%
7 in 10
Marks a paper
5.5
7% of the paper · 10% of the topic
Asked in
24 / 33
Paper 2 sittings · 25 questions
Last asked
May/Jun 2026
9618/23 · Q6 · 13 marks · 11-series streak
Asked in 24 of 33 Paper 2 sittings — about 7 papers in 10.
About 5.5 marks a paper (7% of Paper 2; 10% of the topic's marks across its 4 bullets).
Last asked May/Jun 2026 · 9618/23 · Q6 (13 marks) — in the most recent series.
Asked in each of the last 11 series.
Usually “Complete” or “Describe”: you must produce something — code, a diagram, a table — practise doing it, not reading it.
Biggest chunk of marks so far: 13 in May/Jun 2026 · 9618/23 · Q6.
It is examined almost entirely as AO2 (Apply & analyse, 91%) — you must apply it to the given data or scenario — work it out, trace it, explain it in context.
Last 12 sittings→ Steady
Assessment objectives
AO2 91%
AO1 Knowledge & understanding
AO2 Apply & analyse
AO3 Design, program & evaluate
Complete76%
Describe48%
State24%
Explain24%
Practise its 25 questions Biggest: 13 marks · May/Jun 2026

19% of the topic's marks sit in question parts that belong to another topic (scenario questions cross sections) or that no bullet claims; they count for the topic, not for a bullet.

Marks a paper, year by year

151617181920212223242526

Grey years are the previous syllabus (2015–2021, 84 questions) — history, not counted in the rates.

By exam series

May/Jun17/18 · 33.2 mk
Oct/Nov15/15 · 43.5 mk

Practise 187 real questions Smart Notes Quiz Flashcards Every topic on the Statometer

What you need to know4syllabus §10.1, §10.2, §10.3, §10.4

10.1Data types and records — choosing INTEGER, REAL, CHAR, STRING, BOOLEAN, DATE; defining a record structure and reading from / writing to its fields
10.2Arrays — index, upper and lower bounds; choosing a 1D or 2D array; pseudocode for arrays; bubble sort and linear search on an array
10.3Files — why files are needed; pseudocode to read from and write to text files of one or more lines
10.4Introduction to abstract data types — stacks, queues and linked lists: features, when to use each, adding/editing/deleting data, and how each is implemented with arrays

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Infographics3draw these the way the examiner expects · download as PNG

Bubble sort & linear search

O LevelAS

Stack, queue & linked list

ASA2

Arrays, records & text files

ASO Level

Browse all infographics →

Key terms9use these exact words in the exam

record arrayindextext fileOPENFILEREADFILEWRITEFILEEOFpointer

Dotted terms are defined in the glossary.

Code help4referenced to the Cambridge pseudocode guide

Linked list with parallel arrays

pseudocode §3, §4 Run in Playground

DECLARE Data : ARRAY[1:5] OF INTEGER
DECLARE Link : ARRAY[1:5] OF INTEGER
DECLARE Start, Free, P, Node : INTEGER
// initial free list 1→2→3→4→5
FOR Node ← 1 TO 4
   Link[Node] ← Node + 1
NEXT Node
Link[5] ← 0
Start ← 0
Free ← 1
PROCEDURE AddToFront(V : INTEGER)
   DECLARE N : INTEGER
   N ← Free
   Free ← Link[Free]
   Data[N] ← V
   Link[N] ← Start
   Start ← N
ENDPROCEDURE
CALL AddToFront(30)
CALL AddToFront(20)
CALL AddToFront(10)
P ← Start
WHILE P <> 0
   OUTPUT Data[P]
   P ← Link[P]
ENDWHILE

Record type + array of records + file

pseudocode §4.1–4.2, §9.1 Run in Playground

TYPE Student
   DECLARE Name : STRING
   DECLARE Mark : INTEGER
ENDTYPE
DECLARE Group : ARRAY[1:3] OF Student
DECLARE i : INTEGER
Group[1].Name ← "Ali"
Group[1].Mark ← 71
Group[2].Name ← "Sara"
Group[2].Mark ← 88
Group[3].Name ← "Omar"
Group[3].Mark ← 64
OPENFILE "class.txt" FOR WRITE
FOR i ← 1 TO 3
   WRITEFILE "class.txt", Group[i].Name & "," & NUM_TO_STR(Group[i].Mark)
NEXT i
CLOSEFILE "class.txt"
OUTPUT "Saved — see Files panel"

Linear search and bubble sort on a 1D array (§10.2)

pseudocode 9618 guide §5, §6 Run in Playground

DECLARE Names : ARRAY[1:6] OF STRING
DECLARE i, Last : INTEGER
DECLARE Temp, Target : STRING
DECLARE Found, Swapped : BOOLEAN
Names[1] ← "Zara"
Names[2] ← "Ali"
Names[3] ← "Omar"
Names[4] ← "Bilal"
Names[5] ← "Hina"
Names[6] ← "Sana"
Target ← "Hina"
Found ← FALSE
i ← 1
WHILE i <= 6 AND NOT Found
   IF Names[i] = Target THEN
      Found ← TRUE
   ELSE
      i ← i + 1
   ENDIF
ENDWHILE
IF Found THEN
   OUTPUT Target, " found at index ", i
ELSE
   OUTPUT Target, " not found"
ENDIF
Last ← 5
REPEAT
   Swapped ← FALSE
   FOR i ← 1 TO Last
      IF Names[i] > Names[i + 1] THEN
         Temp ← Names[i]
         Names[i] ← Names[i + 1]
         Names[i + 1] ← Temp
         Swapped ← TRUE
      ENDIF
   NEXT i
   Last ← Last - 1
UNTIL NOT Swapped OR Last = 0
FOR i ← 1 TO 6
   OUTPUT Names[i]
NEXT i

💡 The search stops as soon as the item is found; the sort shortens each pass and stops early when a pass makes no swaps.

Count and total the lines of a text file (§10.3)

pseudocode 9618 guide §9.1 Run in Playground

DECLARE Line : STRING
DECLARE Count, Total : INTEGER
OPENFILE "Scores.txt" FOR WRITE
WRITEFILE "Scores.txt", "45"
WRITEFILE "Scores.txt", "72"
WRITEFILE "Scores.txt", "60"
CLOSEFILE "Scores.txt"
Count ← 0
Total ← 0
OPENFILE "Scores.txt" FOR READ
WHILE NOT EOF("Scores.txt")
   READFILE "Scores.txt", Line
   Count ← Count + 1
   Total ← Total + STR_TO_NUM(Line)
ENDWHILE
CLOSEFILE "Scores.txt"
OUTPUT Count, " lines, total ", Total

💡 Text files hold strings, so each line is converted with STR_TO_NUM before it is added.

Playground examples26runnable programs for this topic

Fill a 1D array with INPUT, output it backwards
Arrays are indexed from 1; a FOR loop visits every element.
O LevelASPseudocodeArrays §3.1–3.2
Run
2D array — marks table with row and column totals
ARRAY[1:3, 1:4]: the first index is the row (student), the second the column (test).
O LevelASPseudocodeArrays §3.1–3.2, §7.1
Run
Whole-array copy & reversed copy
Backup ← Original copies every element at once (same size and type). A reversed copy needs a loop.
ASA2PseudocodeArrays §3.2
Run
Parallel arrays — names and marks
Two arrays share an index: Names[i] belongs with Marks[i].
O LevelASPseudocodeArrays §3.2
Run
Passing an array to a procedure and a function
Fill an array BYREF, then total it with a function.
ASA2PseudocodeProcedures & functions §8.1–8.3
Run
Sort parallel arrays — a leaderboard
Sort marks descending and swap the names at the same time so they stay matched.
ASPseudocodeSorting 9618 §9.2, §10.2
Run
Text file — write then read to EOF
OPENFILE FOR WRITE creates the file; FOR READ plus a WHILE NOT EOF loop reads every line.
O LevelASPseudocodeFile handling §9.1
Run
APPEND to a file & count its lines
WRITE starts a new file; APPEND adds after the existing data.
O LevelASPseudocodeFile handling §9.1
Run
Search a file for a record
Each line is name,mark. Stop reading as soon as the name is found.
ASPseudocodeFile handling §9.1
Run
Save records to a text file and load them back
Write each record as one delimited line, then parse the lines back into an array of records.
ASA2PseudocodeFile handling §4.1, §9.1
Run
A record type
TYPE … ENDTYPE groups fields of different types under one name; access them with a dot.
ASA2PseudocodeRecords & user-defined types §4.1
Run
Array of records — a class register
Register[i].Mark: index the array, then pick the field.
ASA2PseudocodeRecords & user-defined types §4.2
Run
Records with DATE fields & whole-record copy
The guide's StudentRecord: Pupil2 ← Pupil1 copies every field; arrays of records are updated in a loop.
A2PseudocodeRecords & user-defined types §4.1–4.2
Run
Stack — push, pop, overflow & underflow
LIFO with an array and a Top pointer. Watch what happens on the 4th pop.
ASA2PseudocodeStacks, queues, lists & trees 9618 §10.4, §19.1
Run
Linear queue — enqueue & dequeue
FIFO with Front and Rear pointers. Notice the space at the front is never reused.
ASA2PseudocodeStacks, queues, lists & trees 9618 §10.4, §19.1
Run
Linked list in arrays with a free list
Insert at the front, delete by value, traverse — using Data/Pointer records, StartPointer and FreePointer.
ASA2PseudocodeStacks, queues, lists & trees 9618 §10.4, §19.1
Run
AS Paper 2 — library loans
An array of records, a search function, procedures for borrowing and reporting, all driven by a menu.
ASPseudocodeExam-style tasks §4.2, §8
Run
Lists — the Python array
Create, index, change, append, and loop. Remember index 0. len() gives the size.
O LevelASPythonArrays §3.1–3.2 ↔ Python
Run
2D list — seating plan
A list of lists. seat[row][col]. Build it with a comprehension so each row is a separate list.
O LevelASPythonArrays §3.1 ↔ Python
Run
Frequency count with a list and a dictionary
Count dice rolls two ways: a list indexed by value, and a dictionary (the ADT the exam calls a dictionary).
ASA2PythonArrays §3 ↔ Python
Run
Write then read a text file
open() with 'w', 'a' and 'r'; with closes the file for you. The file appears in the Files panel after the run.
O LevelASPythonFile handling §9.1 ↔ Python
Run
Read until end of file, count and total
readline() returns '' at EOF — the Python version of WHILE NOT EOF. Also readlines().
ASPythonFile handling §9.1 ↔ Python
Run
Records in a file — CSV with the csv module
A list of dictionaries written and read back as CSV, the way Paper 4 file-handling questions expect.
A2PythonFile handling §9 ↔ Python
Run
Records — dataclass and dictionary
TYPE … ENDTYPE becomes a dataclass (or a dict). An array of records is a list of them.
ASPythonRecords & user-defined types §4.1 ↔ Python
Run
Enumerated type with Enum
TYPE Season = (Spring, Summer, …) in Python: an Enum with an order.
ASPythonRecords & user-defined types §4.1 ↔ Python
Run
Stack and queue with a list
append/pop give a stack; append/pop(0) a queue. Watch the order things come out.
ASA2PythonStacks, queues, lists & trees §10 ADT ↔ Python
Run

Also for this topic: 11 Java programs · 11 VB.NET programs in the browser compilers.

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Everything for this topic — study hub

Statometer — what 33 real papers say about this topic and each of its 4 syllabus bullets

What you need to know4syllabus §10.1, §10.2, §10.3, §10.4

Video lectures42ZAK's YouTube channel · play here

Queue ADT in Pseudocode · A Level 9618 CS · CS

Stack ADT: Introduction in VB.NET · A Level 9618 CS · CS

Stack ADT: Introduction in Pseudocode · A Level 9618 CS · CS

Text File Handling 101 · O Level · IGCSE · AS Level CS · CS

User Defined Data Types: Enumerated, Pointer and Record (UDT) · A Level 9618 CS · CS

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