Chapter5ArraysandStructures

5.1ArraysArray（數(shù)組）：agroupofvariablesofthesamedatatypeDefineStoreDimensionofthearray:thenumberofelementsinanarrayArrayindex(orsubscript):ThepositionofanelementinanarrayTheindexofthearraynumbersstartswith05.1ArraysArrayHowtorefertoaparticularelement?usethearraynameandtheindexinbracketsHowtoaccessthefinalelement?or?52×√5.1ArraysProgramExampleP5Adefineagesasanarrayof10integersformat:Theforloopisusedtoreadeachelementofthearrayandaddthemtototal_age.5.1ArraysProgramExampleP5B:findtheminimumandmaximumvaluesinanarraydefineaconstantintegerSIZEandanarray“ages”withsizeSIZEsymbolicconstantTheconstkeywordisusedinthedefinitiontospecifythatitsvaluecannotbechanged.Theidentifierisusuallywritteninuppercase.Usingasymbolicconstantmakestheprogrameasiertomodify5.1ArraysProgramExampleP5B:findtheminimumandmaximumvaluesinanarrayTheforlreadsinvaluesintothearrayagesandtotalsthemoopTheforloopcompareseachelementinthearraywiththevaluesyoungestandoldest.Whenages[i]largerthanoldest,itsvalueisassignedtooldest.Whenages[i]lessthanyoungest,itsvalueisassignedtoyoungest.Thesmallestelementofthearrayisinyoungestandthelargestisinoldestwhentheloopiscompleted.5.1ArraysInitializinganarrayProgramExampleP5CDefineandinitializeanarraydays.Theinitialvaluesinthearrayareseparatedby,andplacedbetween{}.5.1ArraysInitializinganarrayWhenthelistofinitialvaluesislessthanthenumberofelementsinthearray,theremainingelementsareinitializedto0.Ifanarrayisdefinedwithoutspecifyingthenumberofelementsandisinitializedtoaseriesofvalues,thenumberofelementsinthearrayistakentobethesameasthenumberofinitialvalues.||5.1ArraysTwo-dimensionalarraysAtwo-dimensionalarrayhasmorethanonerowofelements5.1ArraysTwo-dimensionalarraysDefine:encloseeachdimensionofthearrayinbracketsAccessanelement:specifytherowandthecolumnTherownumberstartsat0andendsat6Thecolumnnumberstartsat0andendsat4.5.1ArraysProgramExampleP5D:readsinthenumberofstudentsusingthefivelaboratoriesoversevendaysSymbolicconstantNO_OF_DAYSandNO_OF_LABS.

Defineatwo-dimensionalarrayusagewithNO_OF_DAYSrowsandNO_OF_LABScolumns.5.1ArraysProgramExampleP5DTheforlooptotalseverycolumnofarrayusageandaveragethem.Theforloopreadsinvaluesintothearrayusage[][]5.1ArraysInitializingatwo-dimensionalarrayInitializedbyenclosingtheinitialvaluesinbracesPlacetheinitialvaluesofeachrowonaseparatelineoraddbracesineachrowtoimprovereadability

5.1ArraysInitializingatwo-dimensionalarrayOmitthefirstdimensionCompilerwillcalculatethenumberofrowsMissingvaluesareinitializedto0

Notethatthefirstdimensionisrequiredhere,why?5.1ArraysMulti-dimensionalarraysDefinearrayswithanynumberofdimensionsTheelementsofthisarrayareaccessedbyusingthreesubscripts5.2Structures5.2.1IntroductionArraysaresuitableforstoringsetsofhomogeneousdataForexample,astudent’stestscoresForitemsofinformationthatarelogicallyrelatedbuteachitemmayhaveadifferentdatatype?Astudent’snumberandtestscoresLogicallyrelateditemsofinformationthatmayhavedifferentdatatypescanbecombinedintoastructure（結(jié)構(gòu)體）5.2Structures5.2.2DeclaringastructureStep1:Declareastructuretemplate:Astructuretemplateconsistsofthereservedkeywordstructfollowedbythenameofthestructure.

structuretag:nameofthestructure

structuremember:eachiteminastructure5.2Structures5.2.2DeclaringastructureStep2:definevariableswiththetypedeclareddefinestudent1andstudent2tobeofthetypestruct

student_rec5.2Structures5.2.2DeclaringastructureAccessmembersofastructurevariable:withthememberselectionoperator“.”ProgramExampleP5E:inputsvaluesforeachmemberofastructureanddisplaysitonthescreen5.2StructuresProgramExampleP5E5.2StructuresProgramExampleP5E5.2StructuresAnotherdeclarationformofastructure5.2Structures5.2.3InitializingastructurevariablePlacetheirinitialvaluesinbracestoinitializeastructure5.2Structures5.2.4NestedstructuresAstructurethatcontainsanotherstructureasoneofitsmembers.5.3Thetypedefstatementtypedefallowstodefineasynonym(同義詞)forabuilt-inoraprogrammerdefineddatatypeUsetypedeftodefineasynonymDATEforstructdate:5.4Arraysofstructures（結(jié)構(gòu)體數(shù)組）Example:Defineafive-elementarraypersons.Eachelementofthisarrayisofthetypestructpersonnelwithmembersnumber,dobandjoinedThemembersdobandjoinedarethemselvesstructuresandhavemembersday,monthandyear.Whichmemberwillbeaccessed?persons[0].number?persons[4].joined.year?5.5Enumerateddatatypes（枚舉數(shù)據(jù)類型）Anenumerateddatatypeisusedtodescribeasetofintegervalues.Thesestatementsdeclarethedatatyperesponsetohaveoneofthreepossiblevalues:no,yes,ornone.answerisdefinedasanenumeratedvariableoftyperesponse.NameoftheenumerateddatatypedefinedresponseiscalledtheenumerationtagThenamesenclosedin{and}mustbeintegerconstantsThevalueofnois0;thevalueofyesis1;thevalueofnoneis2….5.5Enumerateddatatypes（枚舉數(shù)據(jù)類型）Anotherdefinitionformwhentheenumerateddatatypeandtheenumeratedvariablesaredefinedtogether,theenumerationtagisoptio