Data Types & Casting (AQA GCSE Computer Science)

Revision Note

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James Woodhouse

Written by: James Woodhouse

Reviewed by: Lucy Kirkham

Data Types & Casting

What is a data type?

  • 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:

Data type

Used for

Example

Integer

Whole numbers

10, -5, 0

Real

Numbers with a fractional part

3.14, -2.5, 0.0

Character 

Single character

'a', 'B', '6', '£'

String

Sequence of characters

"Hello world", "ABC", "@#!%"

Boolean

True or false values

True, False

  • It is important to choose the correct data type for a given situation to ensure accuracy and efficiency in the program

  • Data types can be changed within a program, this is called casting or String handling operations

  • You can read more about string handling operations and converting data types here

Worked Example

Customers booking a holiday can choose between half board or all inclusive and a hotel star rating between 1 and 5

A typical booking record is shown in the table:

firstName

Jacob

lastName

Franks

boardType

All inclusive

starRating

5

bookingComplete

True

 State the most appropriate data type for the following fields [2]

A simple two-row table with blue headers labeled "boardType" and "starRating" and empty cells beneath.

 Give the name of one field that could be stored as a Boolean data type [1]

Answer

Table with two rows and two columns. First column has "boardType" and "starRating" in blue cells, second column has "String" and "Integer" in green cells.
  • bookingComplete

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James Woodhouse

Author: James Woodhouse

Expertise: Computer Science

James graduated from the University of Sunderland with a degree in ICT and Computing education. He has over 14 years of experience both teaching and leading in Computer Science, specialising in teaching GCSE and A-level. James has held various leadership roles, including Head of Computer Science and coordinator positions for Key Stage 3 and Key Stage 4. James has a keen interest in networking security and technologies aimed at preventing security breaches.

Lucy Kirkham

Author: Lucy Kirkham

Expertise: Head of STEM

Lucy has been a passionate Maths teacher for over 12 years, teaching maths across the UK and abroad helping to engage, interest and develop confidence in the subject at all levels.Working as a Head of Department and then Director of Maths, Lucy has advised schools and academy trusts in both Scotland and the East Midlands, where her role was to support and coach teachers to improve Maths teaching for all.