面向对象中外文翻译.docx

面向对象中外文翻译.docx

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面向对象中外文翻译

学院（部）：

计算机科学与工程学院

专业班级：

计算机09-2班

学生姓名：

指导教师：

2013年5月29日

Object-orientedanalysisanddesign

Thebasicconceptofobject-orientedtechnologyandthebasicmethod

1.1softwaredevelopmentmethod

Computerafterbirth,computertechnologyhasbeendevelopinginhighspeedcondition,thedevelopmentofcomputerscienceandtechnologybyoriginalonlydependsonthedevelopmentofhardwaretorelyingmoreonsoftwaredevelopment.Infact,thedevelopmentofsoftwaretechnologyhasexperiencedmorethangenerationprocess.

Firstgeneration（50to60softhe20thcentury）,inprogramminglanguagessuchasFORTRANandALGOLtechnologymarkedbyalgorithm

Generationtogeneration.Atthattime,theprogramdesignonpeopleallcreativetalents,allrelyontipsandtricks.Softwareproductivityisverylow,basedonthealgorithmprocedureisverydifficulttounderstand,programmerswritetheirownprogramoveraperiodoftimeevenafteroneselfalsolooknottounderstand,thistothesoftwaremodifications,maintenancebringgreatdifficulties.Soattheendofthe60sinthe"softwarecrisis".

Secondgeneration（inthelate1970sto80sprevailing）,suchasPASCAL,andCOBOLprogramminglanguageandrelationaldatabasemanagementsystemforastructuredsystemanalysisanddesigntechniques.Inordertoovercomethesoftwarecrisis,peoplemadeeffortstomainlyfromthefollowingtwodirections:

MethodsfromtheAngleofthemanagementtoimprovethesoftwaredevelopment,softwareengineeringmethodisproposed,andgreatlyimprovethequalityandmaintainabilityofthesoftware.

Secondistofocusontheanalysisinthesoftwaredevelopmentprocessanddesignmethodofresearchandimprovement.Importantachievementsinthisfieldisdevelopedinthe70stherageofstructureddevelopmentmethodofstructuredsystemanalysisanddesigntechniques.

Thirdgeneration（inthe80sisstillprevalent）representedbySmalltalk,c++object-orientedsoftwaredevelopmentmethods.

Question1:

whatisonthedevelopmentdynamicsofobject-orientedsoftwaredevelopmentmethods?

Traditionalstructuredprogrammingalgorithmasthecore,theoriginaliscloselyrelatedtothedataandseparatetotheoperationofthedata,itisdifficulttomaintaintheconsistencyofdataandoperation,itssoftwaredevelopmentmethodalsodoesnotconformtothenaturalthinkinghabits,thedesignedsoftwaresystemsolutionspaceandtheproblemspace,theexpanded,difficulttounderstand,modify,andleadtoproblemsintermsofprogramcomplexityandsoftwarecrisis.Inordertotranscendprogramcomplexitybarrier,overcomethesoftwarecrisis,object-orientedsoftwaredevelopmentmethodsareputforward.

Question2:

whataretheadvantagesoftheobject-orientedsoftwaredevelopmentmethod?

Object-orienteddevelopmentmethodtochangethepasttraditionalonthebasisoffunctionanalysisandfunctiondecompositionofprocessorientedstructuralanalysisanddesignmethodofobject-orienteddevelopmentmethodtosimulatethewaypeopleunderstandanddealwiththeobjectiveworldtoanalyzetheproblem,thesystemasaseriesofcollectionsofobjects,itsobject-orienteddesignandanalysisofresultsismappedtoastructureofobject-orientedimplementationtool,hasamoredirectcorrespondencetomappingprocess,theanalysts,designers,andprogrammerscanusethesameconcept,sothattheobjectorientedsoftwaredevelopmentcansimulatemorenaturallytotheactivitiesoftheobjectiveworld,makingtheproblemspaceandsolutionspaceonthestructureassoonaspossible.Therefore,adoptingtheobject-orientedmethodcanmoreeffectivelydevelopinglargesoftwaresystems.Object-orientedmethodofencapsulation,inheritanceandpolymorphismmechanismnotonlytosupportsoftwarereuse,andthesoftwaremaintenance,reliableandefficientsoftwaresystemwhichcanrealizeflexiblemanufacturing,bettertoovercomethesoftwarecrisis.Therefore,ithasbecomeamaturemethodwidelyusedinsoftwaredevelopment.Bytheendofthe20thcentury,objectorientedsoftwareengineeringdevelopmentgraduallymature,especiallytheformationoftheunifiedmodelinglanguage（UML）standardandwidelyused,theobject-orientedsoftwaredevelopmentmethodshavebecomethemainstreamofthesoftwaredevelopmenttechnology.

1.2thebasicconceptofobject-oriented

Object:

（1）abstractrepresentationsoftheobjectsisanobjectiveentityattributesoftheobjectisdescribedbythedataandthedatafortheoperationofthebehavioroftwoparts.

（2）class:

classisacollectionofobjectswiththesamepropertiesandbehaviorofabstractdescription;Internalincludingattributesandbehavioroftwomainparts.

（3）example:

classesistohavethesamepropertiesandbehaviorofasetofabstractdescriptionsofobjects.Therefore,classescanbeusedasauser-definedtypeandcreatetheobjectmodel,andaccordingtothemodelcreatedbytheactualexampleofaspecificobjectisaclass,oftenreferredtoasexamples.

（4）themessage:

themessageistorequestanobjectitcontainsaprocessingoperationontheinstructioninformation.Essenceistotheoperationoftheobjectofaclassfunctioncall,thecalltoamethod.

Forexample,studentS1;S1.Thedisplay（）isamessage.

Anewsgenerallyconsistsofthreeparts:

receivingamessageobjectname,theparametersofthefunctionname,function,operation.

（5）thethreebasiccharacteristicsofobject-orientedtechnology:

encapsulation,inheritance,andpolymorphism

（6）encapsulation:

theso-calledencapsulationistheobject'spropertiesandbehaviorcombinedintoasingleunit,totheoutsideworldcannotdirectlyaccessormodifythedataandcode,theoutsideworldonlythroughobjectprovidestheinterfacefunctiontochangetheattributesoftheobjectorobtainingdata,itisrealizedthemessageishidden.

（7）inheritance:

ifinadefinedontheclass,addsomespecialattributeoroperation,canformanewclass,thisclassisnotonlyinheritedtheformerallcharacteristicsofaclass,andwithnewfeatures,soasaspecialcaseoftheclassbefore,isinfrontofaclasstoinherit.Aclassknownastheparentclass,beforethenewclassiscalledasubclass.Throughinheritancerelationshipcanformatypehierarchy,calledinheritancestructure.

Polymorphism（8）:

indifferentclasses,thesamefunctionnametorealizefunctionsofdifferentfunctionsavailable.Polymorphismsoftheadvantages:

high-levelcode（algorithm）writeitonlyonceandthelowercanbereusedformanytimes,canimprovetheprogrammingflexibilityandefficiency.

Object-orientedprogramming

1.threemajormechanismsofobjectorientedtechnology（characteristics）:

（1）encapsulationmechanismandthedesignoftheclass:

theso-calledencapsulatedobjectattributedataandoperationmethodisallowedtobecombinedintoasingleunit,totheoutsideworldcannotdirectlyaccessormodifythedataandcode,theoutsideworldonlythroughobjectprovidestheinterfacefunctiontochangetheattributesoftheobjectorobtainingdata,itimplementsthemessagehidden;Inc++,classistosupportthedataencapsulationtool,allowingdesignclassdescriptionstoabstractasetwiththesamepropertiesandbehavioroftheobject,namelycanencapsulateasetofobjectsintheclassofcommonpropertiesandmethods.Thus,classisthetooltorealizedataencapsulation,objectistherealizationofdataencapsulation.Nopackage,noobject-orientedtechnology.

Classmemberstoaccesstheprincipleis:

（1）defineaclass,thedatamembersandmemberfunctionsisthedefaultaccessprivatemembers.

（2）amemberfunctioncanbedirectaccesstothemembersofthesamevariablesandcallstomembersofthesamefunction,neednotaddobjectnamebeforethefunctionname.（3）membersoftheprivateorprotectedmemberislimitedtothescopeoftheclassthatthebodyandtheclassmemberfunctions;Nonmemberfunctionsshouldbedefinedasaclassoffriendstoaccesstheprivatemembersofaclassmemberfunction.（4）membersofthepublicscopenotonlyincludestheclassbody,alsoincludestheuseoftheobjectwhichitbelongs.Canaccesstopublicmembersoutsideclass,butmustbebeforethemembernameplustheobjectname.

（2）theinheritancemechanismandderivedclassdefinition:

theso-calledinheritanceisallowedonanexistingclass,addsomespecialattributesoroperations,toderiveanewclass.Notonlycanthederivedclassinheritsabaseclassmember,andcandefinenewmember,socanbeasspecialclassofaclassbefore.Aclassknownastheparentclass,beforethenewclassiscalledasubclass.Throughinheritancerelationshipcanformatypehierarchy,calledinheritancestructure.InheritanceisoneoftheSharedpropertiesbetweenclassesandservicemechanism.

classperson//Thebaseclass

{protected:

charname[11];

charsex;

intage;

public:

person（）{cout<<“person”<

~person（）{cout<<“deleteperson”<

intGetage（）{return20;}}

classStudent:

publicperson

{private:

charid[9];

floatscore;

public:

student（）{cout<<“student”<

~student（）{cout<<“deletestudent”<

floatGetScore{returnscore;}

}

voidF（person*q）{ q->Getage（）; }

voidmain（）

{person*p;

students;

p=&s;

F（p）;//p->Getage（）;

}

Theresults：

person

student

20

deletestudent

deleteperson

2.Thedefinitionofmechanismofpolymorphismandvirtualfunctions:

Polymorphismreferstotheclasshierarchyinthesameclassordifferentclasses,canusethesamefunctionnamedifferentoperatingfunctionality,whichyoucanusethesamecallwaytoinvokethesefunctionswiththesamenamewithdifferentfunction