Data types (Cambridge International AS Computer Science)

Exam board Cambridge International · ASUpdated 2025-04-30

Primitive data types

What are data types?

A data type is a classification of data into groups according to the kind of data they represent
Computers use different data types to represent different types of data in a program
The basic data types include:
- Integer: used to represent whole numbers, either positive or negative
  - Examples: 10, -5, 0
- Real: used to represent numbers with a fractional part, either positive or negative
  - Examples: 3.14, -2.5, 0.0
- Char: used to represent a single character such as a letter, digit or symbol
  - Examples: 'a', 'B', '5', '$'
- String: used to represent a sequence of alphanumerical characters
  - Examples: "Hello World", "1234", "@#$%"
- Boolean: used to represent true or false values
  - Examples: True, False
- Date: used to store a calendar date
  - Example: DD/MM/YY
It is important to choose the correct data type for a given situation to ensure accuracy and efficiency in the program
In pseudocode and some other programming languages, data types must be declared before they can be used
- The data types are declared with each data item to be used
- Each data item is given a unique name called an identifier
- DECLARE <identifier> : <data type>

Data Type	Example Value	Pseudocode	Python	Java	VB.NET
Integer	`10`	`DECLARE Age : INTEGER` `Age ← 10`	`age = 10`	`int age = 10;`	`Dim age As Integer = 10`
Real	`3.14`	`DECLARE Temp : REAL` `Temp ← 3.14`	`temp = 3.14`	`double temp = 3.14;`	`Dim temp As Double = 3.14`
Char	`'A'`	`DECLARE Grade : CHAR` `Grade ← 'A'`	`grade = 'A'`	`char grade = 'A';`	`Dim grade As Char = "A"c`
String	`"Hello"`	`DECLARE Name : STRING` `Name ← "Hello"`	`name = "Hello"`	`String name = "Hello";`	`Dim name As String = "Hello"`
Boolean	`TRUE`	`DECLARE LoggedIn : BOOLEAN` `LoggedIn ← TRUE`	`logged_in = True`	`boolean loggedIn = true;`	`Dim loggedIn As Boolean = True`
Date	`24/04/2025`	`DECLARE DOB : DATE` `DOB ← "24/04/2025"`	`dob = "24/04/2025"` (string or `datetime`)	`LocalDate dob = LocalDate.of(2025, 4, 24);`	`Dim dob As Date = #24/04/2025#`

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Data Type

Example Value

Pseudocode

Python

Java

VB.NET

Integer

10

DECLARE Age : INTEGER
Age ← 10

age = 10

int age = 10;

Dim age As Integer = 10

Real

3.14

DECLARE Temp : REAL
Temp ← 3.14

temp = 3.14

double temp = 3.14;

Dim temp As Double = 3.14

Char

'A'

DECLARE Grade : CHAR
Grade ← 'A'

grade = 'A'

char grade = 'A';

Dim grade As Char = "A"c

String

"Hello"

DECLARE Name : STRING
Name ← "Hello"

name = "Hello"

String name = "Hello";

Dim name As String = "Hello"

Boolean

TRUE

DECLARE LoggedIn : BOOLEAN
LoggedIn ← TRUE

logged_in = True

boolean loggedIn = true;

Dim loggedIn As Boolean = True

Date

24/04/2025

DECLARE DOB : DATE
DOB ← "24/04/2025"

dob = "24/04/2025" (string or datetime)

LocalDate dob = LocalDate.of(2025, 4, 24);

Dim dob As Date = #24/04/2025#