AQA 8525 · Section 3.2 · 3.2.1

Data
Types

Integer · Real · Boolean · Character · String · Casting

CSZoneAQA GCSE Computer Science 8525

Learning Objectives

By the end of this lesson you will be able to...

Name and describe each of the five AQA data types

Give appropriate examples of values for each data type

Explain the difference between integer and real number types

Describe type casting and why it is needed

The Five AQA Data Types

AQA 8525 — Data Types You Must Know

Data Type	Description	Examples
Integer	Whole numbers (positive, negative, zero)	42, -7, 0, 100
Real	Numbers with a decimal point	3.14, -0.5, 9.99
Boolean	True or False only	True, False
Character	A single character (letter, digit, symbol)	'A', '7', '!'
String	A sequence of zero or more characters	'Hello', '42abc'

Integer vs Real

Choosing the Right Number Type

INTEGER

Use when counting discrete items

No decimal point — whole numbers only

E.g. number of students, score, age

score ← 85

REAL

Use for continuous values requiring precision

Has a decimal point

E.g. temperature, price, weight

price ← 9.99

Boolean & String

Boolean Logic and Strings

BOOLEAN

Only two possible values: True or False. Used in conditions and comparisons.

loggedIn ← True
found ← False
IF score > 50 THEN
pass ← True

STRING

Zero or more characters in quotes. Can contain letters, digits, spaces, and symbols.

name ← 'Ahmed'
empty ← ''
msg ← 'Score: 85'

Type Casting

Converting Between Data Types

Sometimes you need to convert a value from one type to another. AQA pseudocode uses built-in functions for this — called type casting.

Function	Converts to	Example
INT(x)	Integer	INT('42') → 42
REAL(x)	Real	REAL(3) → 3.0
STR(x)	String	STR(85) → '85'
BOOL(x)	Boolean	BOOL(1) → True

Why casting?USERINPUT always returns a string. Use INT() to do arithmetic: age ← INT(USERINPUT)

Exam Practice

Have a go at this question

AQA-style question

State the most appropriate data type for each of the following variables:
(a) A student's name
(b) Whether a door is open or closed
(c) The average score on a test
(d) The number of pupils in a class

4 marks

(a) String [1] (b) Boolean [1] (c) Real [1] (d) Integer [1]

Key Takeaways

What to Remember

AQA 5 types: Integer, Real, Boolean, Character, String

Integer = whole numbers · Real = decimals

Boolean = True/False only · String = sequence of characters in quotes

Use INT(), REAL(), STR() to cast between types — USERINPUT always returns a String!