What values can a Boolean hold?

A Boolean holds only one of two values, True or False. Booleans suit yes-or-no facts such as whether a door is locked.

What is the difference between a character and a string?

A character is a single letter, digit or symbol, such as "G". A string is a sequence of characters, such as "Go home".

Which data type should store a UK phone number such as 07700 900123, and why?

A phone number should be stored as a string. An integer would lose the leading zero and the space, and no arithmetic is done on a phone number.

OCR GCSE Computer Science J277

Systems Architecture

Topic overview CPU components and the fetch-execute cycle Factors affecting CPU performance Embedded systems

Memory and Storage

Topic overview RAM, ROM, cache and virtual memory Secondary storage: magnetic, optical and solid state Data units and storage capacity calculations Binary, denary and hexadecimal conversions Binary addition, overflow and binary shifts Character sets, ASCII and Unicode Bitmap images, colour depth and resolution Sound sampling, sample rate and bit depth Lossy and lossless compression

Computer Networks, Connections and Protocols

Topic overview LANs, WANs and network performance Client-server and peer-to-peer networks Network hardware, DNS, hosting and the cloud Star and mesh topologies Wired and wireless connections, IP and MAC addresses Protocols, standards and layers

Network Security

Topic overview Malware, social engineering and brute-force attacks Denial of service, data interception and SQL injection Identifying and preventing vulnerabilities

Systems Software

Topic overview User interfaces, memory management and multitasking Peripheral, user and file management Utility software

Ethical, Legal, Cultural and Environmental Impacts of Digital Technology

Topic overview Ethical and cultural issues in digital technology Environmental impact of digital technology Privacy and digital technology Computer Science legislation and software licences

Algorithms

Topic overview Abstraction, decomposition and algorithmic thinking Flowcharts, pseudocode and structure diagrams Trace tables and correcting algorithms Linear and binary search Bubble, merge and insertion sort

Programming Fundamentals

Topic overview Variables, constants, operators and assignment Sequence, selection and iteration Data types and casting String manipulation and file handling Arrays, records and SQL Functions, procedures and random numbers

Producing Robust Programs

Topic overview Defensive design, input validation and authentication Writing maintainable code Testing, errors and test data

Boolean Logic

Topic overview Logic gates and truth tables Combining gates in logic diagrams

Programming Languages and Integrated Development Environments

Topic overview High-level and low-level languages and translators The integrated development environment (IDE)

Programming Fundamentals

Data types and casting

3 things to know
J277/02

Overview

Integer, real, Boolean, character and string, choosing the right type for phone numbers, prices and grades, and casting with worked results.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Name five common data types used in programs.

Key term

What is the integer data type?

Key term

What is the real data type?

Questions from this subtopic

Each one with the model answer underneath.

1
Name five common data types used in programs.
Model answer
Five common data types are integer, real, Boolean, character and string.
2
What is the integer data type?
Model answer
An integer is a whole number with no fractional part. Values such as −12, 0 and 450 are integers.
3
What is the real data type?
Model answer
A real is a number that can have a fractional part, such as 3.75. Many languages call the real type a float.
4
What values can a Boolean hold?
Model answer
A Boolean holds only one of two values, True or False. Booleans suit yes-or-no facts such as whether a door is locked.
5
What is the difference between a character and a string?
Model answer
A character is a single letter, digit or symbol, such as "G". A string is a sequence of characters, such as "Go home".
6
Which data type should store a UK phone number such as 07700 900123, and why?
Model answer
A phone number should be stored as a string. An integer would lose the leading zero and the space, and no arithmetic is done on a phone number.

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Systems Architecture

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Computer Networks, Connections and Protocols

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Integer means a whole number with no fractional part.

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