§2.2 Programming Fundamentals

Every program, regardless of language, is built from the same three constructs: sequence (instructions run in order), selection (if-else branches choose between paths), and iteration (loops repeat a block). Data is stored in variables (changeable) or constants (fixed), typed appropriately — integer, real, boolean, character, string — and manipulated using arithmetic, comparison, and boolean operators.

OCR's additional programming techniques extend into data structures and abstraction. Arrays (1D and 2D) group related data under one name. Records group related fields of different types into one entity. File handling (open, read, write, close) allows data to persist beyond a single program run. SQL provides a way to query structured data: SELECT FROM WHERE is the basic pattern. Functions return values; procedures do not — both reduce repetition and improve maintainability. Students at St Leonards write answers in Python; the OCR Exam Reference Language (ERL) is also accepted in the exam.

What students must understand

Variables vs constants: variables can change; constants cannot (e.g. PI = 3.14159)

Operators: arithmetic (+, −, ×, ÷, MOD, DIV, ^), comparison (==, !=, <, >, <=, >=), boolean (AND, OR, NOT)

Input and output: user enters data; program displays results

Assignment: store a value in a variable using ← (ERL) or = (Python)

Data types: Integer (whole number), Real (decimal), Boolean (True/False), Character (single char), String (text)

Casting: converting between data types (e.g. int("42"), str(42))

Sequence: default — execute each line in order

Selection: IF/ELSEIF/ELSE decisions; nested selection; CASE/SWITCH statements

Iteration: FOR count-controlled loops; WHILE/DO-WHILE condition-controlled loops; nesting

String manipulation: length, substring, position, upper/lower case, concatenation

File handling: open → read/write → close; reading line-by-line; writing new data

Records: group multiple fields of different types (e.g. student name + age + grade)

SQL: SELECT, FROM, WHERE to query data from a table; basic pattern only

Arrays: 1D (a list) and 2D (a grid); indexed from 0 (Python) or 1 (ERL) — know both

Sub-programs: functions (return a value) vs procedures (perform an action, no return value)

Random number generation: produce random integers or floats within a range

Core constructs (OCR ERL)

What students must understand

Linking questions

Practice

Video Support