计算机英语 教学课件 作者 杨芸 主编 杨 蕾 李连弟 副主编unit6.ppt

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1、UnitsixProgrammingLanguageProgrammingLanguageIntroductionProgramminglanguages，incomputerscience，aretheartificiallanguagesusedtowriteasequenceofinstructions（acomputerprogram）thatcanberunbyacomputer.Similartonaturallanguages，suchasEnglish，programminglanguageshaveavocabulary，grammar，

2、andsyntax.However，naturallanguagesarenotsuitedforprogrammingcomputersbecausetheyareambiguous，meaningthattheirvocabularyandgrammaticalstructuremaybeinterpretedinmultipleways.Thelanguagesusedtoprogramcomputersmusthavesimplelogicalstructures，andtherulesfortheirgrammar，spelling,andpun

3、ctuationmustbeprecise.Programminglanguagesvarygreatlyintheirsophisticationandintheirdegreeofversatility.Someprogramminglanguagesarewrittentoaddressaparticularkindofcomputingproblemorforuseonaparticularmodelofcomputersystem.Forinstance，programminglanguagessuchasFORTRANandCOBOLwerew

4、rittentosolvecertaingeneraltypesofprogrammingproblems－FORTRANforscientificapplications；andCOBOLforbusinessapplications.Althoughtheselanguagesweredesignedtoaddressspecificcategoriesofcomputerproblems，theyarehighlyportable，meaningthattheymaybeusedtoprogrammanytypesofcomputers.Otherl

5、anguages，suchasmachinelanguages，aredesignedtobeusedbyonespecificmodelofcomputersystem，orevenbyonespecificcomputerincertainresearchapplications.Themostcommonlyusedprogramminglanguagesarehighlyportableandbeusedtoeffectivelysolvediversetypesofcomputingproblems.LanguageslikeC，PASCAL，a

6、ndBASICfallintothiscategory.LanguageTypesProgramminglanguagescanbeclassifiedaseitherlow-levellanguagesorhigh-levellanguages.Low-levelprogramminglanguages，ormachinelanguages，arethemostbasictypeofprogramminglanguagesandcanbeunderstooddirectlybyacomputer.Machinelanguagesdifferdependi

7、ngonthemanufacturerandmodelofcomputer.High-levellanguagesareprogramminglanguagesthatmustfirstbetranslatedintoamachinelanguagebeforetheycanbeunderstoodandprocessedbyacomputer.Examplesofhigh-levellanguagesareC，C++，PASCAL，andFORTRAN.Assemblylanguagesareintermediatelanguagesthatarever

8、yclosetomachinelanguagesanddonoth