C-程序设计教学课件CHAPTER-1-Object-Oriented-Programming

C++ProgrammingCHAPTER1Object-OrientedProgramming

1.1Introduction

1.2Object-OrientedandProceduralProgramming

1.3ClassesandAbstractDataTypes

1.4TheClient/ServerModelandMessagePassing

1.5InheritanceandPolymorphism

1.6InterfacesandComponents21.1IntroductionProgrammingLanguagesThegenesisofthecomputerrevolutionwasinamachine.Thegenesisofourprogramminglanguagesthustendstolooklikethatmachine.31.1Introduction1MachineLanguage:Binaryinstruction,whichisalsocalledaninstructionsystem,istheonlyoneuseddirectlybycomputers.Example：Addition100101Subtraction01001141.1Introduction2AssemblyLanguage:Theassemblerlanguageisakindofsymboliclanguage.Itadoptedsomemnemonicsymbolswhichcanshowtheinstructionalfunctionstopresentthecontentoftheprogram.Example：AdditionaddSubtractionsub51.1Introduction3High-levellanguage:ItisaprogramminglanguagebasedonEnglish.Itsoperatorsandexpressionsaresimilartoordinarymathematicalformulas.Example：inta,b,c,d;a=10;b=5;c=8;d=a+b–c;FORTRAN，BASIC，PASCAL，C61.1Introduction4Object-orientedprogramminglanguages:Theyhavethreecharacteristicsincommon:encapsulation,polymorphismandinheritance.Example:Smalltalk，LISP，C++，Java，C#；71.1IntroductionAlgorithmsAlgorithmsaremethodsforsolvingproblemswhicharesuitedforcomputerimplementation.81.1IntroductionDataStructureDatastructureisthetypeandorganizationofdatainaprogram.91.2Object-OrientedandProceduralProgrammingProceduralProgrammingProceduralprogrammingisassociatedwithadesigntechniqueknownastop-downdesign.Intop-downdesign,aproblemisassociatedwithaprocedure.Example:C,Pascal.101.2Object-OrientedandProceduralProgrammingObject-OrientedProgrammingObject-orientedprogrammingisanalternativetoproceduralprogramming.Thedesigntechniqueassociatedwithobject-orientedprogrammingisobject-orienteddesign.Inanobject-orientedprogram,themodulesareclassesratherthanprocedures.111.2Object-OrientedandProceduralProgrammingAristotlewasprobablythefirsttobeginacarefulstudyoftheconceptoftype;hespokeof“theclassoffishesandtheclassofbirds.”Inobject-orienteddesign,aclassisacollectionofobjects.121.2Object-OrientedandProceduralProgrammingObjectsinaclassshareproperties,features,orattributes.Forexample,ifHumanisauser-defineddatatypeinC++,wecandefineavariablesuchasmaryLeakeytorepresenttheobjectwhobelongstotheclassofhumanbeings.Justlike:HumanmaryLeakey;131.2Object-OrientedandProceduralProgrammingInC++,themembervariablesorfieldsarecalleddatamembers.Thefunctionsthatbelongtoaclassarecalledfunctionmembers.Inobject-orientedlanguagesgenerally,suchfunctionsarecalledmethods.141.3ClassesandAbstractDataTypesInformationHidingInanobject-orientedlanguage,aclassisamodulethatsupportsinformationhiding.InaC++class,wecanusekeywordssuchaspublicandprivatetocontrolaccesstotheclass’spropertiesandoperations.151.3ClassesandAbstractDataTypesEncapsulationInproceduralprogramming,dataaremanipulatedbyprocedureswithpassingargumentstoandreturningavaluefromafunction.161.3ClassesandAbstractDataTypesInobject-orientedprogramming,dataandtheprocedurestomanipulatethedatacanbeencapsulatedorcontainedwithinaclass.171.3ClassesandAbstractDataTypesAbstractDataTypeAdatatypeisabstractifitexposesinitspublicinterfaceonlyhigh-leveloperationsandhidesalllow-levelimplementationdetails.Forexample,theclassesinC++,whichprovideinformationhiding,areabstractdatatypes.181.4TheClient/ServerModelandMessagePassingClient/ServerModelObject-orientedprogrammingisbasedonclient/servermodelofcomputing.Thismodelexplainstheemphasisplacedoninformationhidinginobject-orientedprogramming.191.4TheClient/ServerModelandMessagePassingExample:#include<string>usingnamespacestd;intmain(){strings1=”HelloWorld!”;intn=s1.length();return0;}TheC++programthatusesthestringclassisaclient.Aclientrequestsservicesfromastringobjectbyinvokingoneofitsmethods,whichischaracterizedassendingamessagetotheobject.201.4TheClient/ServerModelandMessagePassingMessagePassing#include<string>usingnamespacestd;intmain(){strings1=”HelloWorld!”;intn=s1.length();return0;}211.4TheClient/ServerModelandMessagePassingobjectDatamembersFuctionmembersFuctionmembersobjectmessagemessageobjectDatamembersDatamembersFuctionmembersFuctionmembersmessageFuctionmembersFuctionmembers221.5InheritanceandPolymorphismClassescanbestand-aloneortheycanoccurininheritancehierarchies,whichconsistofparent/childrelationshipsamongclasses.parrentchild231.5InheritanceandPolymorphismInheritanceOneofthemostcompellingfeaturesaboutC++iscodereuse.Inheritancesupportsaformofcodereuse.241.5InheritanceandPolymorphismPolymorphismThetermpolymorphismmeanshavingmanyforms.Polymorphismallowsimprovedcodeorganizationandreadabilityaswellasthecreationofextensibleprogramsthatcanbe“grown”notonlyduringtheoriginalcreationoftheproject,butalsowhennewfeaturesaredesired.251.6InterfacesandComponentsInterfacesInterfaces,ifwellbuiltandsharedamongclasses,areaconveniencetoprogrammers.Learningashared