Strings, Records and One- and Two-dimensional Arrays
Choosing, indexing and processing structured collections while distinguishing characters, strings, records and arrays.
How to study for GCSE Computer Science
Move repeatedly between problem, algorithm, trace, code, test evidence and system explanation; use the exact language and assessment format required by your current board.
Core concepts
Concept 1
A string is an ordered sequence of characters, while an array stores indexed elements under a defined structure.
Exam cue: Choose a record when fields describe one entity and an array when repeated elements share a structure.
Concept 2
A record groups related fields that may have different types to represent one entity.
Exam cue: State index bounds before tracing or writing a loop.
Concept 3
One-dimensional arrays model lists and two-dimensional arrays model grids or tables, with valid index ranges determined by the language or notation.
Exam cue: Use nested iteration for two-dimensional structures and keep row and column roles consistent.
Risk pitfalls and guardrails
Treating a character and a one-character string as universally interchangeable.
Guardrail: Do not substitute one board's syntax, protocol list, language version or extension topic for the multi-board core; check the current specification and exam year.
Assuming every board's reference language starts array indices at the same value.
Guardrail: Do not substitute one board's syntax, protocol list, language version or extension topic for the multi-board core; check the current specification and exam year.
Swapping row and column indices midway through an algorithm.
Guardrail: Do not substitute one board's syntax, protocol list, language version or extension topic for the multi-board core; check the current specification and exam year.
Memory anchors
String
An ordered sequence of characters treated as a data value.
Array
An indexed collection of elements arranged in a defined structure.
Record
A group of named fields representing one structured item.
Index
A position used to access an element in an ordered structure.
Two-dimensional array
An array addressed using two indices, commonly representing rows and columns.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
What is an array?
Why is an array useful for storing 30 daily temperatures?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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