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There are no more sales.2 Search for records containing the term. There are still recordscontaining the term.3 Total extra items. Extra items remain.4 Search member records. There are no more records.5 Print all addresses. There are still addresses available.6 Display client names. There are no names remaining.7 List all guests. There are no guests left.8 Total monthly sales. There are no more sales for the current year.UNIT 21 Software Engineering149Flowcharts are sometimes used for designing parts ofprograms. Describe this extract from a program flowchart using thestructures revised in this unit and the sequence expressions listed inUnit 2, Task 11.Fig 3Hotel accommodationinvoicing flowchart150UNIT 21 Software EngineeringSPEAKINGWork in pairs, A and B.
You each have information about someprogramming languages. Together decide what would be the mostappropriate language to use for each of these situations.123456789101112A schoolteacher wants his young pupils to learn some basicmathematics by controlling a simple robot.The owner of a small business wants to create a simpledatabase program to keep track of his stock.An engineer wants to develop a program for calculating thestresses in a mechanical device.A student wants to create webpages for a personal website.A systems programmer wants to add some new modules to anoperating system.A programmer working for the US army wants to create aprogram for controlling a new type of weapon.A finance company needs to process data from its branchoffices on its mainframe computer.A website designer wants to enable the data on his website tobe easily processed by a number of different programs.A student studying artificial intelligence wants to write someprograms for a course project.A college lecturer wants his students to learn the principles ofprogramming.A professional programmer wants to create and sell a programfor use in language learning.A website designer wants to password-protect a section of awebsite.Student AStudent BYour languages are on page 188.Your languages are on page 194.UNIT 21 Software EngineeringWRITING151Converting to a new system Write a paragraph describingeach of these strategies for converting to a new computer system.Explain what its advantages and disadvantages are.
The first strategyis described for you as an example.1 Direct implementation:all-at-once changeOLD SYSTEM2 Parallel implementation:run at the same time3 Phased implementation:parts of the system areconverted separatelya graduallyb in groupsOLD SYSTEMOLD SYSTEM4 Pilot implementation:tried first in only onepart of the companyOLD SYSTEMNEW SYSTEMFig 4Strategies for converting to a new computer system1Direct implementation:Direct implementation means that the user simply stops usingthe old system and starts using the new one. The advantage isthat you do not have to run two systems at the same time.
Thedisadvantage of this approach is that if the new system does notoperate properly, there is nothing to fall back on.152UNIT 21 Software EngineeringSPECIALIST READINGOBJECT-ORIENTED PROGRAMMINGDOne of the principal motivations for using OOPis to handle multimedia applications in whichsuch diverse data types as sound and video canbe packaged together into executable modules.Another is writing program code that's moreintuitive and reusable; in other words, code thatshortens program-development time.12345678Find the answers to these questions in thefollowing text.What advantages of using object-orientedprogramming are mentioned in the text?What are the three key features of OOP?What multimedia data types are referred toin the text?List the different types of triangle mentionedin the text.What feature avoids the problem of decidinghow each separate type of data is integratedand synchronized into a working whole?What specific type of rectangle is named inthe text?What common properties of a rectangle arementioned in the text?What features are made quicker by codereusability?Perhaps the key feature of OOP is encapsulation- bundling data and program instructions intomodules called 'objects'.
Here's an example ofhow objects work. An icon on a display screenmight be called ' Triangles'. When the user selectsthe Triangles icon - which is an object composedof the properties of triangles (see fig. below) andother data and instructions - a menu mightappear on the screen offering several choices.The choices may be (1) create a new triangle and(2) fetch a triangle already in storage. The menu,too, is an object, as are the choices on it.
Eachtime a user selects an object, instructions insidethe object are executed with whatever propertiesor data the object holds, to get to the next step.For instance, when the user wants to create aABOUT OBJECTSObjects can be classes, subclasses, orinstances. A class is at the highest levelof the hierarchy.
Classes are furtherrefined into subclasses. Instances arespecific occurrences in a class or subclass.RECTILINEAR SHAPESSTRAIGHTLINESINHERITANCEProperties in a class are inherited bytheir subclasses or instances. Thus, allrectilinear shapes are assumed topossess straight lines and no curves.RECTILINEAR SHAPESRIGHT TRIANGLECONTAINSRIGHT ANGLESCLASS OR SUBCLASSINSTANCEPROPERTYUNIT 21 Software Engineeringtriangle, the application might execute a set ofinstructions that displays several types oftriangles - right, equilateral, isosceles, and so on.Many industry observers feel that theencapsulation feature of OOP is the natural toolfor complex applications in which speech andmoving images are integrated with text andgraphics. With moving images and voice builtinto the objects themselves, program developersavoid the sticky problem of deciding how eachseparate type of data is to be integrated andsynchronized into a working whole.A second key feature of OOP is inheritance.
Thisallows OOP developers to define one class ofobjects, say 'Rectangles', and a specific instanceof this class, say 'Squares' (a rectangle with equalsides). Thus, all properties of rectangles - 'Has 4sides' and 'Contains 4 right angles' are the twoshown here - are automatically inherited bySquares.
Inheritance is a useful property inrapidly processing business data. For instance,consider a business that has a class called'Employees at the Dearborn Plant' and a specificinstance of this class, 'Welders'. If employees atthe Dearborn plant are eligible for a specificbenefits package, welders automatically qualifyfor the package. If a welder named John Smith islater relocated from Dearborn to Birmingham,Alabama, where a different benefits package isavailable, revision is simple.
An iconrepresenting John Smith - such as John Smith'sface - can be selected on the screen and draggedwith a mouse to an icon representing theBirmingham plant. He then automatically'inherits' the Birmingham benefit package.A third principle behind OOP is polymorphism.This means that different objects can receive thesame instructions but deal with them in differentways. For instance, consider again the trianglesexample.
If the user right clicks the mouse on'Right triangle', a voice clip might explain theproperties of right triangles. However, if themouse is right clicked on 'Equilateral triangle'the voice instead explains properties ofequilateral triangles.The combination of encapsulation, inheritanceand polymorphism leads to code reusability.'Reusable code' means that new programs caneasily be copied and pasted together from oldprograms. All one has to do is access a library ofobjects and stitch them into a working whole.This eliminates the need to write code fromscratch and then debug it. Code reusabilitymakes both program development and programmaintenance faster.[Adapted from 'Understanding Computers Today and Tomorrow',1998 edition, Charles S.
Parker, The Dryden Press]B153Re-read the text to find the answers tothese questions.1 Match the terms in Table A with thestatements in Table B.Table AaOOPbEncapsulationcObjectdMenue SquarefPolymorphismgLibraryTable Bi An OOP property that allows data andprogram instructions to be bundled intoan objectii A list of choicesiii An OOP property that enables differentobjects to deal with the same instructionin different waysiv A reusable collection of objectsv A module containing data and programinstructionsviObject-Oriented Programmingvii A rectangle with equal sides2Complete the following text using wordsfrom the reading text:Encapsulation,and polymorphism arekey features ofprogramming.Encapsulation allows data and programinstructions to be bundled together incalled objects. Inheritance means that specificof a class of objectstheproperties of the class of objects.
Polymorphismmeans that instructions are treated differently bydifferentThe combination of thesefeatures of OOP means that programcode is reusable. This speeds upandof programs.-UNIT 22People in ComputingSTARTERWhat do the following people in computing do? Compareanswers with your partner.1 Webmaster2 Help-desk troubleshooter3 Applications programmer4 Security specialist5 Systems programmerREADINGWork in groups of three: A, B and C. Read your text andcomplete this table. You may not find information for each section ofyour table.B1 job title2nature of work3 formal qualifications4 personal qualities5 technical skills6how to get started7how to make progressHow to become a programming expertThe primary requirements for being a goodprogrammer are nothing more than a goodmemory, an attention to detail, a logical mind andthe ability to work through a problem in amethodical manner breaking tasks down intosmaller, more manageable pieces.So what specific skills are employers looking for?The Windows market is booming and there's ademand for good C, C++, Delphi, Java and VisualBasic developers.
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