What is a programming paradigm?

A style or approach to programming - a whole way of thinking about how a program should be organised and what a program fundamentally is. It determines how the problem is broken down, how data and instructions are represented and how the flow of the program is controlled, rather than merely which keywords are typed.

Why is there a need for more than one programming paradigm?

Different kinds of problem have different natural shapes, and a paradigm that fits the shape of the problem produces code that is shorter, clearer and less likely to be wrong. Controlling a machine step by step suits a procedural approach; modelling a system of interacting real-world things suits objects; expressing a set of facts and rules and letting the machine search suits a declarative approach; responding to unpredictable user actions suits an event-driven one. Hardware and the size of projects have also changed over time, and paradigms developed to manage the growing complexity.

What characterises the procedural paradigm?

The program is a sequence of instructions telling the computer step by step what to do, in a stated order, using the three basic constructs of sequence, selection and iteration. Data is held in variables that the instructions read and change, and the instructions are grouped into procedures and functions that can be called from elsewhere. It is imperative: the code says how the task is to be carried out.

What characterises the object-oriented paradigm?

The program is organised as a set of objects that each bundle together their own data and the operations that act on it, and that interact by calling one another's methods. Objects are created from classes, which act as templates, and classes can inherit from other classes. Data is deliberately hidden inside objects rather than being globally available.

OCR A-Level Computer Science H446

Processors: Structure, Performance and Types

Topic overview Inside the CPU: ALU, control unit, registers and buses The fetch-decode-execute cycle What makes a CPU fast: clock speed, cores and cache Pipelining Von Neumann, Harvard and contemporary architecture CISC and RISC GPUs, multicore and parallel systems

Input, Output and Storage

Topic overview Choosing input and output devices for a problem Magnetic, flash and optical storage RAM and ROM Virtual storage and disk thrashing

Systems Software

Topic overview Operating systems: need, function and purpose Memory management: paging, segmentation and virtual memory Interrupts and the interrupt service routine Scheduling algorithms: first come first served, round robin and shortest job first Scheduling algorithms: shortest remaining time, multi-level feedback queues, traces and choosing an algorithm Types of operating system BIOS, device drivers and virtual machines

Applications Generation

Topic overview Applications and utilities Open source and closed source Translators: interpreters, compilers and assemblers The stages of compilation Linkers, loaders and libraries

Software Development

Topic overview The five development methodologies Choosing a methodology: merits, drawbacks and fit Writing and following algorithms

Types of Programming Language

Topic overview Programming paradigms and procedural languages Assembly language and the Little Man Computer Modes of addressing memory Object-oriented programming: classes and objects, attributes and methods, encapsulation Object-oriented programming: inheritance, polymorphism, advantages and disadvantages

Exchanging Data

Topic overview Compression Encryption Hashing Flat file and relational databases, keys and indexing Referential integrity, entity relationship diagrams and database management systems Normalisation to 3NF SQL: Interpreting and Modifying Queries Capturing, Selecting, Managing and Exchanging Data Transaction Processing, ACID, Record Locking and Redundancy

Networks

Topic overview Characteristics of networks, LANs and WANs, protocols and standards Protocol layering and the TCP/IP stack DNS and the structure of the internet Packet and circuit switching Network security and threats Firewalls, proxies and encryption Network hardware Client-server and peer to peer

Web Technologies

Topic overview Structure, presentation and behaviour, and HTML CSS JavaScript Server side and client side processing Search engine indexing The PageRank algorithm

Data Types and Number Representation

Topic overview Primitive data types Binary, hexadecimal and denary conversion Negative numbers: sign and magnitude and two's complement Binary addition, subtraction and overflow Floating point representation and normalisation Floating point addition and subtraction, and fixed point compared Bitwise shifts Masks with AND, OR and XOR Character sets: ASCII and Unicode

Data Structures

Topic overview Arrays and records Lists and tuples, and creating, traversing, adding and removing items Linked Lists Stacks Queues and Circular Queues Graphs Trees and binary search trees: structure, insertion and searching Deleting from a binary search tree, traversals, uses of trees and general trees Hash Tables

Boolean Algebra

Topic overview Logic Gates and Truth Tables Defining Problems Using Boolean Logic Boolean Algebra Rules and Simplification Karnaugh Maps Half Adders, Full Adders and D-type Flip Flops

Legal, Moral, Cultural and Ethical Issues

Topic overview Computing related legislation: Data Protection Act 1998 Computing related legislation: Computer Misuse Act 1990 Computing related legislation: Copyright, Designs and Patents Act 1988 Computing related legislation: Regulation of Investigatory Powers Act 2000 Moral and ethical issues: computers in the workforce, automated decision making and artificial intelligence Moral and ethical issues: environmental effects, censorship, monitoring behaviour and analysing personal information Moral and ethical issues: piracy, offensive communications, layout, colour and character sets

Elements of Computational Thinking

Topic overview Thinking abstractly Thinking ahead Thinking procedurally Thinking logically Thinking concurrently

Problem Solving and Programming

Topic overview Programming techniques: Programming constructs Programming techniques: Recursion Programming techniques: Global and local variables Programming techniques: modularity, functions and procedures, and parameter passing Programming techniques: Use of an IDE to develop/debug a program Programming techniques: Use of object oriented techniques Computational methods: solvable problems, problem recognition, decomposition, and divide and conquer Computational methods: Use of abstraction and backtracking Computational methods: data mining, heuristics and performance modelling Computational methods: pipelining, visualisation and choosing a method

Algorithms

Topic overview Designing and analysing an algorithm Measuring efficiency and Big O notation Comparing algorithms and choosing one for a task Stacks Queues Linked lists Trees and binary search trees Traversing a tree: depth-first and breadth-first Bubble sort Insertion sort Merge sort Quick sort Comparing the four sorting algorithms Linear search Binary search Dijkstra's shortest path algorithm The A* algorithm

Types of Programming Language

5 subtopics
13 things to know
Component 01

What Types of Programming Language covers

Types of Programming Language is examined on component 01 of OCR Computer Science, Computer systems. 64 recall questions across 5 subtopics.

Where it is assessed

Component 01

Computer systems, the whole of the first paper.

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The 5 subtopics

Each one has its own page.

What you need to know

Answer each one before you reveal it.

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Key term

Name three features you would expect to find in a procedural language.

Key term

What characterises a declarative paradigm, and how does it differ from an imperative one?

Key term

What characterises the logic paradigm?

Key term

In the Little Man Computer, what is the difference between BRA, BRZ and BRP?

Key term

A student uses BRP to loop while a counter is greater than zero, and finds the loop runs one time too many. Explain.

Key term

In immediate addressing, what does the operand actually mean?

Key term

In direct addressing, what does the operand actually mean?

Key term

What is an attribute?

Key term

Explain the difference between an attribute and a method, and between a class and an object.

Key term

What is inheritance?

Key term

Give an example of inheritance with a superclass and two subclasses.

Key term

What is polymorphism?

Key term

Name the four modes of addressing memory.

Take Types of Programming Language further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

A class vs An object
A class: the template defining the attributes and methods that its instances will have. An object: one instance created from that template, with its own values.
An attribute vs A method
An attribute: a data item belonging to an object, describing part of its state. A method: a procedure belonging to an object, defining something it can do.
Encapsulation vs Inheritance
Encapsulation: keeping an object's data private and reachable only through its own procedures. Inheritance: defining a new class that takes on the members of an existing one and extends them.

Questions from this topic

Each one with the model answer underneath.

1
What is a programming paradigm?
Model answer
A style or approach to programming - a whole way of thinking about how a program should be organised and what a program fundamentally is. It determines how the problem is broken down, how data and instructions are represented and how the flow of the program is controlled, rather than merely which keywords are typed.
2
Why is there a need for more than one programming paradigm?
Model answer
Different kinds of problem have different natural shapes, and a paradigm that fits the shape of the problem produces code that is shorter, clearer and less likely to be wrong. Controlling a machine step by step suits a procedural approach; modelling a system of interacting real-world things suits objects; expressing a set of facts and rules and letting the machine search suits a declarative approach; responding to unpredictable user actions suits an event-driven one. Hardware and the size of projects have also changed over time, and paradigms developed to manage the growing complexity.
3
What characterises the procedural paradigm?
Model answer
The program is a sequence of instructions telling the computer step by step what to do, in a stated order, using the three basic constructs of sequence, selection and iteration. Data is held in variables that the instructions read and change, and the instructions are grouped into procedures and functions that can be called from elsewhere. It is imperative: the code says how the task is to be carried out.
4
Name three features you would expect to find in a procedural language.
Model answer
Variables and data types for storing values; the control constructs of sequence, selection and iteration; subroutines - procedures and functions - with parameters and local variables; and usually arrays and other structured data types. Examples of procedural languages include C, Pascal and Python used in a procedural style.
5
What characterises the object-oriented paradigm?
Model answer
The program is organised as a set of objects that each bundle together their own data and the operations that act on it, and that interact by calling one another's methods. Objects are created from classes, which act as templates, and classes can inherit from other classes. Data is deliberately hidden inside objects rather than being globally available.
6
What characterises a declarative paradigm, and how does it differ from an imperative one?
Model answer
A declarative program states what is wanted rather than how to obtain it, leaving the system to work out the steps. An imperative program - procedural or object-oriented - spells out the sequence of operations. A database query that asks for all customers in a given town is declarative; a loop that examines each record in turn and adds the matching ones to a list is imperative.

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Types of Programming Language revision questions

What does Types of Programming Language cover in OCR A-Level Computer Science?: 5 subtopics: programming paradigms and procedural languages, assembly language and the little man computer, modes of addressing memory, object-oriented programming: classes and objects, attributes and methods, encapsulation and object-oriented programming: inheritance, polymorphism, advantages and disadvantages. Each one has its own page with questions and model answers.
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