REVISION INFORMATION Software Development Life Cycle Software Development Tools High Level Programming:

Structures Algorithms Iteration Pseudocode

Order of Priority and Relational Operators

SOFTWARE DEVELOPMENT LIFE CYCLE

A

Dance

In

The

Dark

Every

Monday

ANALYSISAnalysis is about understanding the problem.

Start by describing the problem, as you see it, in your own words as clearly and concisely as possible.

Identify all required inputs. (external information)

Identify all required processes. (calculations, decisions, comparisons)

Identify all required outputs. (anything which must be shown on the screen or output in any other way)

DESIGNAt this stage the designers will set out how the problem will be solved. They will design various aspects of the program using:

storyboards testplan pseudocode graphical design notation (flowcharts)

shows the overall structure of the program clearly

IMPLEMENTATION

Actually writing all the program code using a software development program e.g. Java, C++, Visual Basic.

Software development programs provide a text editor that you use to write high level language code

TESTING normal conditions

the program does what it should do with normal input e.g. the user has to enter a number between 1 and 100

extreme conditionsthe program can handle situations that are at the edge of what would be considered normal

exceptional conditions it can handle inputs that it has not been designed to cope with

e.g. A program is being written to record scores rolled on a six-sided dicethe most suitable set of test data : 3, 1, 0, 7, 6, 2

DOCUMENTATION

The types of documentation generated at this stage often include:

technical guide information about the spec of computer required

user guide step by step guide on how to use the program description of the features of the software

EVALUATION

checking whether the program is readable

does the solution solve the problem

the issues encountered

the issues outstanding

recommendations for improvement

MAINTENANCEprogram maintenance may be required when

new bugs are uncovered by the end-user

new requirements are identified at a later date the client requires the original solution to be

integrated with other systems

TRANSLATORSTranslates high level languages (written by humans) into machine code (understood by processors)

There are two main types of translator programs.

Compiler translates a program into machine code (commands that are

written in ones and zeroes)

Interpreter does the same as a compiler but one line at a time

SCRIPTING LANGUAGE AND MACROS

Small programs called macros can be developed within some application packages e.g. Word Processing, Spreadsheets.

The macro is actually coded in a scripting language called Visual BASIC for Applications(VBA)

A Macro is a set of commands activated by a single keystroke.

PRE-DEFINED FUNCTIONSThere are some standard pre-defined functions that you may

want to use in your programs.

Pre-defined functions: greatly speed up program development

Int takes a number and removes any fractional part leaving the whole

number part isKeyDown

retrieves keyboard input

STANDARD ALGORITHMSAn algorithm is a finite sequence of steps that solves a specific problem. For this unit, you need to know about 4 standard algorithms.

finding a minimum finding a maximum counting occurrences linear search

STANDARD ALGORITHMSExample: a list of daily midday temperatures recorded at a weather station during February 2003

The find a minimum algorithm would search through all the daily temperatures in the list, and find the lowest one i.e. (2°C)

date 1 2 3 4 5 6 7 8 9 10

11

12

13

14

temperature (°C)

4 6 5 7 11

9 8 5 3 4 3 6 7 4

date 15

16

17

18

19

20

21

22

23

24

25

26

27

28

temperature (°C)

5 6 2 3 8 6 12

10

11

9 6 11

8 6

STANDARD ALGORITHMS

find maximum works its way through a list of numbers and finds the number with the highest value i.e. (12°C) counting occurrences

counts how many occurrences of a given value there are in the list

Linear search searches through a list looking for a particular item and

reports where the item is found

ARRAYS

All of the standard algorithms which you met in the last slides operate on a list of data items.

We will see how a computer program can store a list of items

ARRAYSSuppose a program was required which would prompt the user to enter and store the names and scores for nine dart players.Variables required:first_name, second_name, third_name, fourth_name …… ninth_name (all strings)

first_score, second_score, third_score, fourth_score …… ninth_score (all numbers).

ARRAYS

Instead of creating 18 individual variables you create 2 arrays:

An array of strings: string[] names = new string[5];

An array of numbersint[] marks = new int[5];

LOOPS Fixed loop the number of times a section of code is to be repeated is fixed in

advanceFor(i=0; i<5; i++) {Lines of code}

Conditional loop A section of code in a program is to be repeated until a

particular item of data is entered by the user while (i < 10)

{Lines of code}

BODMASBRACKETS, OPEN, DIVIDE, MULTIPLY, ADD, SUBTRACT

Arithmetic operators +, -, *, /

Which one of the following would be the output from the line of program code below?

PRINT 5 + 3 * 4 – 1 312416

RELATIONAL OPERATORS== != > < >= <=

A ticket program will give a discount if the person is under 16 or if the person is 65 and over

Age > 65 AND age < 16Age > 65 OR age < 16Age > = 65 AND age < 16Age > = 65 OR age < 16

PSEUDOCODEMix of English and programming language and can help when converting to code

let score be 24if score is greater than or equal to 30 display “A Pass”if score is greater than or equal to 24 and less than 30 display “B Pass”if score is greater than or equal to 16 and less than 24 display “C Pass”if score is less than 16 display “Fail”

In the code sample above, what type of statement is the first line? let score be 23

Conditional loopFixed loopConditional statementAssignment

  What is the output on screen from the code section above?

A PassB PassC PassFail

  What program construct is being used in the section of pseudocode shown above?

A fixed loopA conditional loopConditional statementsAn arithmetical operation