A Practical Introduction to Pascal — with BS 6192

250 Pages·1982·17.395 MB·English

by  I. R. Wilson, A. M. Addyman (auth.)

ISBN 978-0-333-33340-2
9 780333 333402
Macmillan ComputerScienceSeries
ConsultingEditor
ProfessorF.H.Sumner,UniversityofManchester
S.T.AllworthandR.N.Zobel, Introduction toReal-timeSoftwareDesign.
secondedition
IanO.Angell andGarethGriffith,High-resolutionComputerGraphicsUsing
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IanO.Angell andGarethGriffith,High-resolutionComputerGraphics UsingPascal
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B.G.Blundell,e.N.Daskalakis,N.A.E.Heyes andT.P.Hopkins,An
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P.e.CaponandPJ.Jinks, CompilerEngineeringUsingPascal
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P.Jaulent, L.BaticleandP.Pillot,68020-30Microprocessorsandtheir
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lRWilsonandA.M.Addyman,APracticalIntroductiontoPascal- withBS6I92.
secondedition
Non-series
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10.Angell,AdvancedGraphicswiththeIBMPersonalComputer
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A Practical
Introduction to
Pascal
-with BS 6192
Second Edition
I.R.Wilson
Department ofComputer Science, University ofManchester
A.M.Addyman
Department ofMathematics and Computer Science,
University ofSalford
M
MACMILLAN
©I.R.WilsonandA.M.Addyman 1978.1982
©BS6192: 1982.BritishStandards Institution
Allrightsreserved.Noreproduction.copyortransmission
ofthispublicationmaybemade withoutwrittenpermission.
Noparagraphofthispublicationmaybereproduced.copiedor
transmitted savewithwrittenpermissionorinaccordance with
theprovisionsoftheCopyright,DesignsandPatentsAct 1988,
orunderthetermsofanylicencepermitting limitedcopying
issuedbytheCopyright LicensingAgency,33--4AlfredPlace.
London WCIE7DP.
Anypersonwhodoesanyunauthorisedactinrelationto
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civilclaimsfordamages.
Firstedition 1978
Reprinted 1979(twice), 1980(twice), 1981
Secondedition 1982
Reprinted 1983(withminorcorrections).1984(twice),1985,
1987. 1990
Publishedby
MACMILLAN EDUCATIONLTD
Houndmills,Basingstoke,HampshireRG212XS
andLondon
Companiesandrepresentatives
throughout theworld
Typesetin 10/12PressRomanby
ThamesTypesetting,Abingdon .
ISBN 978-0-333-33340-2 ISBN 978-1-349-06364-2 (eBook)
DOI 10.1007/978-1-349-06364-2
to
Alleyn, Fiona,Jamie, Kirstie
Hilary, Rebecca, Sarah, Helen and Amy
Contents
Preface
xi
Introduction
I
2 TheForm ofaProgramandBasicCalculations 4
2.1 TheStyleofWritinginPascal 4
2.2 TheGeneralFormofaProgram 4
2.3 TheAssignmentStatementandSimpleArithmetic 5
2.4 ACompleteProgramwithSimpleInput/Output 6
2.5 ReadablePrograms 7
3 BasicControlConstructs 9
3.1 Repetition 9
3.2 Choice-TheifStatement 13
3.3 Selection-ThecaseStatement 16
3.4 AdviceonProblem-solving 17
4 Variables,Constantsand Expressions 21
4.1 TheDifferentTypesofVariableandConstant 21
4.2 ThePrecedenceofOperators 21
4.3 Real 22
4.4 Integer 23
4.5 Character 2S
4.6 TheBasisofDecisions-Boolean 27
4.7 MoreComplexConditions 28
5 AnIntroductionto InputandOutput 32
5.1 readandreadln 32
5.2 write andwriteln 33
5.3 TheDifferentStylesofOutput 35
6 AnIntroductionto ProceduresandFunctions 38
6.1 CallingandDefiningaProcedure 38
6.2 VaryingtheAction-ValueParameters 39
6.3 ObtainingResults-VariableParameters 40
6.4 CalculatingOneValue-Functions 42
6.5 TheScopeofIdentiflers 44
viii APracticalIntroductiontoPascal
7 DataTypes 48
7.1 The Concept ofType 48
7.2 Type Definitions 49
7.3 SimpleTypes 50
7.4 StructuredDataTypes 55
7.5 DataRepresentation 55
7.6 Type Compatibility 56
7.7 UsingOrdinalTypes 57
7.8 PrintingonaFixedWidthPrinter 58
8 StructuringMethods I-TheSequentialFile 61
8.1 The Concept ofaSequence 61
8.2 The Sequential File 61
8.3 InternalandExternal Files 64
804 Textfiles 64
8.5 ASimpleTextEditor 66
9 StructuringMethods2-TheSet 70
9.1 AnIntroductionto SetTheory 70
9.2 SetsinPascal 71
9.3 ABingo-playingProgram 74
10 StructuringMethods3-TheArray 78
10.1 AnIntroductionto Arrays 78
10.2 ArraysofArrays 79
10.3 Arraysofchar 80
lOA Packingand Unpacking 81
10.5 TheArrayinUse 82
10.6 ConformantArrayParameters 86
11 StructuringMethods4-TheRecord 93
II.l AnIntroductionto Records 93
11.2 Records inPascal 93
II.3 Thewith Statement 95
11.4 ASimpleApplicationofRecords-ACardGame 97
12 StructuringMethods5- TheVariant 102
12.1 The NeedforType Unions 102
12.2 Record VariantsinPascal 103
12.3 UsingRecordVariants 105
1204 CalculatingtheAreaofaGeometric Figure 105
Contents ix
13 AdvancedUsesofProceduresand Functions 107
13.1 TheUseofProcedures forTop-down Design 107
13.2 AfurtherDiscussionofScope 108
13.3 Procedural andFunctionalParameters 110
13.4 Recursion 112
13.5 TheDirectiveforward 115
13.6 Thegoto Statement 116
13.7 Restrictionsontheuseofgotosand Labels 117
14 DynamicDataStructures 119
14.1 Static and DynamicVariables 119
14.2 TheCreation ofDynamicVariables 121
14.3 UsingPointers 122
14.4 Re-usingDynamicallyAllocated Storage 124
14.5 TheLondon Underground Problem 125
AppendixI PascalSyntaxDiagrams 135
AppendixII ListofPascalReservedWords 143
AppendixIII AnswerstoExercisesandSchemaforSelectedProblems 144
Bibliography 162
ThePascalStandard 163
Index 237
Preface
Sincethe firsteditionofthis book waswrittenin1977,there hasbeena
tremendousincreaseintheuseofPascal.Thisincreasedusehashad two
significanteffects.
(1) Ithasproducedabetterunderstandingofthe facilitiesofPascalandtheir
use.
(2) Ithasfosteredthe productionofthe ISOstandardforPascal.
Thissecondeditionreflects both this betterunderstandingandthe
clarificationsandchangesto Pascalwhichhaveresultedfrom theproduction
ofthe BSljlSO Pascalstandard.Thestandard(BS6I92,whichsuppliesthe
technicalcontentforISO7185) isthe definitivedocumentonPascal;it is
reproducedinitsentiretyfrom page163ofthe book. Mywork onthe
PascalStandardhasconvinced methat the descriptionofaprogramming
languagemay betutorial,oritmaybedefmitive, oritmaybeneither! The
chaptersofthis book donot constituteadefmitive descriptionofPascal.They
areessentiallytutorial.
The book isbasedonanintroductorylecturecoursegivenatManchester. In
additionto lectures, the courseconsistsoftwo kindsofpractical work. The
firstisbasedonthe solution ofshort pencil-and-paper exercises.Thesecond
requiresthe studentto write completeprogramsandrun them usinginteractive
computerterminals.Eachchapterofthe book concludeswith exercisesand
problemssuitable forthese purposes.Although solutions to allofthese arenot
presentedinthe book,teaching staffmay obtainthem byapplicationto the
authors.
The fullPascallanguageispresentedinapractical manner, with reference to
exampleapplications.Theimportanceofthe designofdata structuresinthe
solution ofaproblemisrecognisedbydevotingsevenchaptersto thistopic. It
isintendedthatthe book willbeofuseto first-timestudentsand tomore
experiencedprogrammersnot yet familiarwith Pascal.
Finally,Iwouldliketo thankallthose people from many countrieswhohave
helped mefulfilmyambitionofcreating anISOPascalstandardandwhoat
the sametimehaveimproved myunderstandingofPascal.Spacepreventsme
fromnamingthemall,but specialmentionshould bemade ofBillFindlay,
ChrisKirkham,Jim Miner,BillPrice,ArthurSale,DavidWattandJimWelsh.