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Cambridge IGCSE GCSE Computer Science

Cambridge: Programming concepts and databases — Cambridge IGCSE GCSE Computer Science revision

Free revision notes, key terms, common exam traps and 5 practice questions with answers. About 8 minutes to read.

Core programming concepts

  • Data types: INTEGER, REAL, CHAR, STRING and BOOLEAN. Declare variables (values that change) and constants (values that do not) with meaningful identifiers.
  • The three basic constructs are sequence, selection (IF, CASE) and iteration (FOR, WHILE, REPEAT). Nested constructs combine them.
  • Operators: arithmetic (+ − * / MOD DIV), comparison (=, <>, <, >, <=, >=) and logical (AND, OR, NOT). MOD gives the remainder and DIV the whole-number quotient.

Arrays, procedures and files

  • One-dimensional arrays store lists indexed by position; two-dimensional arrays store tables addressed by row and column and are usually processed with nested loops.
  • Procedures perform a task, functions return a value, and both can take parameters. Using subroutines makes programs modular, reusable and easier to test — a key Cambridge assessment point.
  • File handling: OPENFILE for READ or WRITE, READFILE / WRITEFILE line by line, and CLOSEFILE when finished. Text files allow data to persist after the program ends.

Key terms

Variable
Named storage whose value can change during execution.
Constant
Named value that cannot change while the program runs.
Array
Data structure storing multiple values of the same type under one identifier.
Procedure
A subroutine that performs a task without returning a value.
Function
A subroutine that returns a value.
Parameter
A value passed into a subroutine.

Common exam traps

  • Using = for comparison and assignment inconsistently; Cambridge pseudocode uses ← for assignment.
  • Forgetting that array indexes must stay within the declared bounds.
  • Confusing MOD (remainder) with DIV (whole-number division).

Practice questions with answers

  1. 1. Which data type stores TRUE or FALSE?

    • • INTEGER
    • • STRING
    • • BOOLEAN
    • • REAL

    Answer: BOOLEAN

    Boolean values are used in conditions.

  2. 2. State the difference between a variable and a constant.

    Answer: A variable's value can change during execution; a constant's cannot

    Constants improve readability and safety.

  3. 3. 17 MOD 5 gives:

    • • 3
    • • 2
    • • 3.4
    • • 5

    Answer: 2

    MOD returns the remainder.

  4. 4. 17 DIV 5 gives:

    • • 2
    • • 3
    • • 3.4
    • • 4

    Answer: 3

    DIV returns the whole-number quotient.

  5. 5. Write pseudocode to declare an array of 10 integers called Scores.

    Answer: DECLARE Scores : ARRAY[1:10] OF INTEGER

    Cambridge syntax uses bounds and a data type.

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