Explain how top-down design is used in a procedural program.

The overall task is broken into smaller sub-tasks, and each sub-task into smaller ones again. Each of the lowest level tasks becomes a procedure or function.

State one advantage of dividing a procedural program into subroutines.

A subroutine can be written, tested and corrected independently of the rest of the program. Several programmers can then work on one project at the same time.

State one disadvantage of the procedural paradigm on very large projects.

Data and the operations on it are kept apart, so a change to a data structure affects many procedures. Dependencies of that kind grow harder to track as the program grows.

Eduqas A-Level Computer Science A500QS

Data Structures: Arrays, Records and Hash Tables

Topic overview One-dimensional arrays and indexing Two- and three-dimensional arrays Manipulating arrays: insertion, deletion and searching Records and fields Arrays of records and record manipulation Hash tables, hashing and collisions Choosing and justifying a data structure

Stacks, Queues, Linked Lists and Trees

Topic overview Stacks: push, pop and the stack pointer Implementing a stack in an array Queues: enqueue, dequeue and pointers Circular queues and priority queues Linked lists: nodes, pointers and the free list Binary trees: nodes, roots and leaves Traversing linked lists and trees

Boolean Logic and Simplification

Topic overview AND, OR and NOT truth tables XOR, NAND and NOR truth tables Truth tables for combined Boolean expressions Boolean identities and rules De Morgan's laws Simplifying Boolean expressions Logical operators in programs, masking and encryption

Algorithms, Pseudo-Code and Programming Constructs

Topic overview Algorithms and how they are defined Pseudo-code conventions Flowcharts and flowchart symbols Sequence and selection Repetition: count-controlled and condition-controlled loops Counts, totals and rogue values Tracing, altering and writing algorithms

Variables, Scope, Parameters and Identifiers

Topic overview Variables and constants Self-documenting identifiers Annotation and program layout Scope of variables: local and global Lifetime of variables Procedure calling, parameters and return values Call by value and call by reference

Recursion and Modular Programming

Topic overview Recursion and the base case How recursive calls use the stack Recursive algorithms: factorial and Fibonacci Recursion compared with iteration Integer division with DIV and MOD Standard functions and standard modules User defined subprograms and modular design

Sorting Algorithms

Topic overview Why a variety of sorting algorithms is needed Bubble sort Insertion sort Quicksort Comparisons, exchanges and passes Storage space and sorting efficiency Writing and altering sort algorithms

Searching and Shortest-Path Algorithms

Topic overview Linear search Binary search Comparing linear and binary search Graphs, weights and the shortest-path problem Dijkstra's shortest-path algorithm Tracing a shortest-path algorithm by hand Choosing the right searching technique

Big O Notation and Algorithm Efficiency

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Validation, Verification and Testing

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Data Compression

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Programming Paradigms and Computer Languages

Topic overview Programming paradigms and where each is used Procedural programming Event-driven and visual programming Mark-up languages Object-oriented programming: objects, classes and methods Ambiguity in natural language and the standardisation of languages Backus-Naur form and syntax diagrams High-level and low-level languages, and choosing one

Systems Analysis, Maintenance and Documentation

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System Design and Human-Computer Interaction

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Software Engineering Tools and Translators

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Computing, Society and the Law

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Computer Architecture, the Processor and Assembly Language

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Input, Output and Secondary Storage

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Networks, Protocols and the Internet

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Data Transmission and Network Performance

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Number Systems and Binary Arithmetic

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Data Types, Characters and Floating Point

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Files, Records and File Organisation

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Databases, Normalisation and Entity Modelling

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SQL, Big Data and Distributed Systems

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The Operating System and Its Modes

Topic overview The need for an operating system and the role of the kernel Managing peripherals, processes and memory protection The user interface and the layers between user and hardware Directory structures and file attributes Utility software Batch processing, real time control and real time transaction systems Types of operating system: single-user, multi-user, multi-tasking and multi-programming Designing an interface for different users and environments

Interrupts, Memory Management and Scheduling

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Types of Software System

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Data Security, Cryptography and Attack

Topic overview Online updating and the integrity of shared files Dangers of holding personal data Clerical procedures, access levels, passwords and write protection Cryptography: its purpose, and symmetric and asymmetric keys Hashing, digital signatures and certificates Caesar and Vernam ciphers and comparing cipher strength Biometric technologies and their limitations Threats, damage and contingency planning Malicious software, hacking and penetration testing

Programming Paradigms and Computer Languages

Procedural programming

3 things to know
Component 1

Overview

Distinguishing features of procedural programming, three basic constructs from which any procedural program is built and structured programming.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Describe the distinguishing features of procedural programming.

Key term

Name the three basic constructs from which any procedural program is built.

Key term

What is meant by structured programming?

Questions from this subtopic

Each one with the model answer underneath.

1
Describe the distinguishing features of procedural programming.
Model answer
A procedural program is a sequence of instructions grouped into procedures and functions. Data is held separately from the code that acts on it.
2
Name the three basic constructs from which any procedural program is built.
Model answer
Sequence, selection and iteration are the three constructs. Any algorithm can be expressed using only those three.
3
What is meant by structured programming?
Model answer
Structured programming builds a program only from the three basic constructs and named subroutines. Unrestricted jumps between parts of the code are avoided.
4
Explain how top-down design is used in a procedural program.
Model answer
The overall task is broken into smaller sub-tasks, and each sub-task into smaller ones again. Each of the lowest level tasks becomes a procedure or function.
5
State one advantage of dividing a procedural program into subroutines.
Model answer
A subroutine can be written, tested and corrected independently of the rest of the program. Several programmers can then work on one project at the same time.
6
State one disadvantage of the procedural paradigm on very large projects.
Model answer
Data and the operations on it are kept apart, so a change to a data structure affects many procedures. Dependencies of that kind grow harder to track as the program grows.

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Data Structures: Arrays, Records and Hash Tables

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Boolean Logic and Simplification

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