C语言学习第五章(英文版)课件.ppt

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1、Chapter5Functions5.1Introduction5.2ProgramModulesinC5.3MathLibraryFunctions5.4Functions5.5FunctionDefinitions5.6FunctionPrototypes5.7CallingFunctions:CallbyValue5.8StorageClasses5.9ScopeRules5.10Recursion5.11ExampleUsingRecursion:TheFibonacciSeries5.12Recursionvs.Iterat

2、ionOutlineFunctionDefinitionsFunctionPrototypesCallingFunctions:CallbyValueStorageClassesScopeRulesRecursionRecursionvs.IterationKeyPointsWhatisafunctionAfunctionisaself-containedblockofstatementsthatperformatask.EveryCprogramcanbethoughtofasacollectionofthesefunctions.

3、5.1Introduction5.1IntroductionDivideandconquerConstructaprogramfromsmallerpiecesorcomponentsThesesmallerpiecesarecalledmodulesEachpiecemoremanageablethantheoriginalprogram5.1IntroductionAgroupofdeclarationsandstatementsthatisassignedanameeffectively,anamedstatementblock

4、usuallyhasavalueAsub-programwhenwewriteourprogramwealwaysdefineafunctionnamedmaininsidemainwecancallotherfunctionswhichcanthemselvesuseotherfunctions,andsoon…5.1Introduction#includevoidmessage();voidmain(){message();printf(“cry,andyoustopthemonotony!”);}voidm

5、essate(){printf(“Smile,andtheworldsmileswithyou…”)；}5.2ProgramModulesinCFunctionsModulesinCProgramscombineuser-definedfunctionswithlibraryfunctionsCstandardlibraryhasawidevarietyoffunctionsFunctioncallsInvokingfunctionsProvidefunctionnameandarguments(data)Functionperf

6、ormsoperationsormanipulationsFunctionreturnsresultsFunctioncallanalogy:BossasksworkertocompletetaskWorkergetsinformation,doestask,returnsresultInformationhiding:bossdoesnotknowdetails5.2ProgramModulesinC--Example-Squareintmain(void){doublenum=0.0,sqr=0.0;printf("enteran

7、umber");scanf("%lf",&num);sqr=square(num);printf("squareof%gis%g",num,sqr);return0;}Thisisafunctiondefinedoutsidemaindoublesquare(doublea){returna*a;}Hereiswherewecallthefunctionsquare5.2ProgramModulesinCWhyusefunctionsWritingfunctionsavoidsrewritingthesamecodeovera

8、ndover.printfandscanfaregoodexamples…Breakyourproblemdownintosmallersub-taskseasiertosolvecomplexproblemsTheym