Data types

Data types - Programming - AQA - GCSE Computer Science Revision - AQA - BBC Bitesize (2024)

Each has a data type. The data type determines what type of value the variable will hold.

Data type	Purpose	Example
Integer	Whole numbers	27
Real	Decimal numbers	27.5
Character	A single alphanumeric character	A
String	One or more alphanumeric characters	ABC
Boolean	TRUE/FALSE	TRUE

Data type	Integer
Purpose	Whole numbers
Example	27

Data type	Real
Purpose	Decimal numbers
Example	27.5

Data type	Character
Purpose	A single alphanumeric character
Example	A

Data type	String
Purpose	One or more alphanumeric characters
Example	ABC

Data type	Boolean
Purpose	TRUE/FALSE
Example	TRUE

Different data types have limitations:

integers and real numbers cannot be concatenated, ie joined together.
numbers held in strings cannot be subject to mathematical operations.

Casting

Sometimes a programmer needs to change the data type of the contents of a variable. For example, an integer may need to be converted to a string in order to be displayed as part of a message. This process is known as casting. The following examples in Python convert a string to an integer and an integer to a string:

str(68) returns “68”int(“54”) returns 54

The three basic programming concepts