编译原理龙书答案完整性高第二章2.2ExercisesforSection2.22.2.1Considerthecontext-freegrammar:S->SS+|SS*|aShowhowthestringaa+a*canbegeneratedbythisgrammar.Constructaparsetreeforthisstring.Whatlanguagedoesthisgrammargenerate?Justifyyouranswer.answerS->SS*->SS+S*->aS+S*->aa+S*->aa+a*L={Postfixexpressionconsistingofdigits,plusandmultiplesigns}2.2.2Whatlanguageisgeneratedbythefollowinggrammars?Ineachcasejustifyyouranswer.S->0S1|01S->+SS|-SS|aS->S(S)S|εS->aSbS|bSaS|ε⧗S->a|S+S|SS|S*|(S)answerL={0n1n|n>=1}L={Prefixexpressionconsistingofplusandminussigns}L={Matchedbracketsofarbitraryarrangementandnesting,includesε}L={Stringhasthesameamountofaandb,includesε}?2.2.3WhichofthegrammarsinExercise2.2.2areambiguousanswerNoNoYesYesYes2.2.4Constructunambiguouscontext-freegrammarsforeachofthefollowinglanguages.Ineachcaseshowthatyourgrammariscorrect.Arithmeticexpressionsinpostfixnotation.Left-associativelistsofidentifiersseparatedbycommas.Right-associativelistsofidentifiersseparatedbycommas.Arithmeticexpressionsofintegersandidentifierswiththefourbinaryoperators+,-,*,/.answer1.E->EEop|num2.list->list,id|id3.list->id,list|id4.expr->expr+term|expr-term|termterm->term*factor|term/factor|factorfactor->id|num|(expr)5.expr->expr+term|expr-term|termterm->term*unary|term/unary|unaryunary->+factor|-factorfactor->id|num|(expr)2.2.5Showthatallbinarystringsgeneratedbythefollowinggrammarhavevaluesdivisibleby3.Hint.Useinductiononthenumberofnodesinaparsetree.num->11|1001|num0|numnumDoesthegrammargenerateallbinarystringswithvaluesdivisibleby3?answerproveanystringderivedfromthegrammarcanbeconsideredtobeasequenceconsistingof11,1001and0,andnotprefixedwith0.thesumofthisstringis:sum=Σn(21+20)*2n+Σm(23+20)*2m=Σn3*2n+Σm9*2mItisobviouslycandivisibleby3.No.Considerstring"10101",itisdivisibleby3,butcannotderivedfromthegrammar.Question:anygeneralprove?2.2.6Constructacontext-freegrammarforromannumerals.Note:wejustconsiderasubsetofromannumeralswhichislessthan4k.answerwikipedia:Roman_numeralsviawikipedia,wecancategorizethesinglenomannumeralsinto4groups:I,II,III|IV|V,VI,VII,VIII|IXthengettheproduction:digit->smallDigit|IV|VsmallDigit|IXsmallDigit->I|II|III|εandwecanfindasimplewaytomapromantoarabicnumerals.Forexample:XII=>X,II=>10+2=>12CXCIX=>C,XC,IX=>100+90+9=>199MDCCCLXXX=>M,DCCC,LXXX=>1000+800+80=>1880viatheuppertworules,wecanderivetheproduction:romanNum->thousandhundredtendigitthousand->M|MM|MMM|εhundred->smallHundred|CD|DsmallHundred|CMsmallHundred->C|CC|CCC|εten->smallTen|XL|LsmallTen|XCsmallTen->X|XX|XXX|εdigit->smallDigit|IV|VsmallDigit|IXsmallDigit->I|II|III|ε2.3ExercisesforSection2.32.3.1Constructasyntax-directedtranslationschemethattrans­latesarithmeticexpressionsfrominfixnotationintoprefixnotationinwhichanoperatorappearsbeforeitsoperands;e.g.,-xyistheprefixnotationforx-y.Giveannotatedparsetreesfortheinputs9-5+2and9-5*2.。
answerproductions:expr->expr+term|expr-term|termterm->term*factor|term/factor|factorfactor->digit|(expr)translationschemes:expr->{print("+")}expr+term|{print("-")}expr-term|termterm->{print("*")}term*factor|{print("/")}term/factor|factorfactor->digit{print(digit)}|(expr)2.3.2Constructasyntax-directedtranslationschemethattrans­latesarithmeticexpressionsfrompostfixnotationintoinfixnotation.Giveannotatedparsetreesfortheinputs95-2*and952*-.answerproductions:expr->exprexpr+|exprexpr-|exprexpr*|exprexpr/|digittranslationschemes:expr->expr{print("+")}expr+|expr{print("-")}expr-|{print("(")}expr{print(")*(")}expr{print(")")}*|{print("(")}expr{print(")/(")}expr{print(")")}/|digit{print(digit)}AnotherreferenceanswerE->{print("(")}E{print(op)}E{print(")"}}op|digit{print(digit)}2.3.3Constructasyntax-directedtranslationschemethattrans­latesintegersintoromannumeralsanswerassistantfunction:repeat(sign,times)//repeat('a',2)='aa'translationschemes:num->thousandhundredtendigit{num.roman=thousand.roman||hundred.roman||ten.roman||digit.roman;print(num.roman)}thousand->low{thousand.roman=repeat('M',low.v)}hundred->low{hundred.roman=repeat('C',low.v)}|4{hundred.roman='CD'}|high{hundred.roman='D'||repeat('X',high.v-5)}|9{hundred.roman='CM'}ten->low{ten.roman=repeat('X',low.v)}|4{ten.roman='XL'}|high{ten.roman='L'||repeat('X',high.v-5)}|9{ten.roman='XC'}digit->low{digit.roman=repeat('I',low.v)}|4{digit.roman='IV'}|high{digit.roman='V'||repeat('I',high.v-5)}|9{digit.roman='IX'}low->0{low.v=0}|1{low.v=1}|2{low.v=2}|3{low.v=3}high->5{high.v=5}|6{high.v=6}|7{high.v=7}|8{high.v=8}2.3.4Constructasyntax-directedtranslationschemethattrans­latesromannumeralsintointegers.answerproductions:romanNum->thousandhundredtendigitthousand->M|MM|MMM|εhundred->smallHundred|CD|DsmallHundred|CMsmallHundred->C|CC|CCC|εten->smallTen|XL|LsmallTen|XCsmallTen->X|XX|XXX|εdigit->smallDigit|IV|VsmallDigit|IXsmallDigit->I|II|III|εtranslationschemes:romanNum->thousandhundredtendigit{romanNum.v=thousand.v||hundred.v||ten.v||digit.v;print(romanNun.v)}thousand->M{thousand.v=1}|MM{thousand.v=2}|MMM{thousand.v=3}|ε{thousand.v=0}hundred->smallHundred{hundred.v=smallHundred.v}|CD{hundred.v=smallHundred.v}|DsmallHundred{hundred.v=5+smallHundred.v}|CM{hundred.v=9}smallHundred->C{smallHundred.v=1}|CC{smallHundred.v=2}|CCC{smallHundred.v=3}|ε{hundred.v=0}ten->smallTen{ten.v=smallTen.v}|XL{ten.v=4}|LsmallTen{ten.v=5+smallTen.v}|XC{ten.v=9}smallTen->X{smallTen.v=1}|XX{smallTen.v=2}|XXX{smallTen.v=3}|ε{smallTen.v=0}digit->smallDigit{digit.v=smallDigit.v}|IV{digit.v=4}|VsmallDigit{digit.v=5+smallDigit.v}|IX{digit.v=9}smallDigit->I{smallDigit.v=1}|II{smallDigit.v=2}|III{smallDigit.v=3}|ε{smallDigit.v=0}2.3.5Constructasyntax-directedtranslationschemethattrans­latespostfixarithmeticexpressionsintoequivalentprefixarithmeticexpressions.answerproduction:expr->exprexprop|digittranslationscheme:expr->{print(op)}exprexprop|digit{print(digit)}ExercisesforSection2.42.4.1Constructrecursive-descentparsers,startingwiththefollow­inggrammars:S->+SS|-SS|aS->S(S)S|εS->0S1|01Answer1)S->+SS|-SS|avoidS(){switch(lookahead){case"+":match("+");S();S();break;case"-":match("-");S();S();break;case"a":match("a");break;default:thrownewSyntaxException();}}voidmatch(Terminalt){if(lookahead=t){lookahead=nextTerminal();}else{thrownewSyntaxException()}}2)S->S(S)S|εvoidS(){if(lookahead=="("){S();match("(");S();match(")");S();}}3)S->0S1|01voidS(){switch(lookahead){case"0":match("0");S();match("1");break;case"1"://match(epsilon);break;default:thrownewSyntaxException();}}ExercisesforSection2.62.6.1ExtendthelexicalanalyzerinSection2.6.5toremovecom­ments,definedasfollows:Acommentbeginswith//andincludesallcharactersuntiltheendofthatline.Acommentbeginswith/*andincludesallcharactersthroughthenextoccurrenceofthecharactersequence*/.2.6.2ExtendthelexicalanalyzerinSection2.6.5torecognizetherelationaloperators.2.6.3ExtendthelexicalanalyzerinSection2.6.5torecognizefloat­ingpointnumberssuchas2.,3.14,and.5.AnswerSourcecode:commit8dd1a9aCodesnippet(src/lexer/Lexer.java):publicTokenscan()throwsIOException,SyntaxException{for(;;peek=(char)stream.read()){if(peek==''||peek=='\t'){continue;}elseif(peek=='\n'){line=line+1;}else{break;}}//handlecommentif(peek=='/'){peek=(char)stream.read();if(peek=='/'){//singlelinecommentfor(;;peek=(char)stream.read()){if(peek=='\n'){break;}}}elseif(peek=='*'){//blockcommentcharprevPeek='';for(;;prevPeek=peek,peek=(char)stream.read()){if(prevPeek=='*'&&peek=='/'){break;}}}else{thrownewSyntaxException();}}//handlerelationsignif("".indexOf(peek)>-1){StringBufferb=newStringBuffer();b.append(peek);peek=(char)stream.read();if(peek=='='){b.append(peek);}returnnewRel(b.toString());}//handlenumber,notypesensitiveif(Character.isDigit(peek)||peek=='.'){BooleanisDotExist=false;StringBufferb=newStringBuffer();do{if(peek=='.'){isDotExist=true;}b.append(peek);peek=(char)stream.read();}while(isDotExist==true?Character.isDigit(peek):Character.isDigit(peek)||peek=='.');returnnewNum(newFloat(b.toString()));}//handlewordif(Character.isLetter(peek)){StringBufferb=newStringBuffer();do{b.append(peek);peek=(char)stream.read();}while(Character.isLetterOrDigit(peek));Strings=b.toString();Wordw=words.get(s);if(w==null){w=newWord(Tag.ID,s);words.put(s,w);}returnw;}Tokent=newToken(peek);peek='';returnt;}ExercisesforSection2.82.8.1For-statementsinCandJavahavetheform:for(exprl;expr2;expr3)stmtThefirstexpressionisexecutedbeforetheloop;itistypicallyusedforinitializ­ingtheloopindex.Thesecondexpressionisatestmadebeforeeachiterationoftheloop;theloopisexitediftheexpressionbecomesO.Theloopitselfcanbethoughtofasthestatement{stmtexpr3;}.Thethirdexpressionisexecutedattheendofeachiteration;itistypicallyusedtoincrementtheloopindex.Themeaningofthefor-statementissimilartoexpr1;while(expr2){stmtexpr3;}DefineaclassForforfor-statements,similartoclassIfinFig.2.43.AnswerclassForextendsStmt{ExprE1;ExprE2;ExprE3;StmtS;publicFor(Exprexpr1,Exprexpr2,Exprexpr3,Stmtstmt){E1=expr1;E2=expr2;E3=expr3;S=stmt;}publicvoidgen(){E1.gen();Labelstart=newLable();Lalelend=newLable();emit("ifFalse"+E2.rvalue().toString()+"goto"+end);S.gen();E3.gen();emit("goto"+start);emit(end+":")}}2.8.2TheprogramminglanguageCdoesnothaveabooleantype.ShowhowaCcompilermighttranslateanif-statementintothree-addresscode.AnswerReplaceemit("isFalse"+E.rvalue().toString()+"goto"+after);withemit("ifNotEqual"+E.rvalue().toString()+"0goto"+after);oremit("isNotEqualZero"+E.rvalue().toString()+"goto"+after);
2025/11/27 8:37:48 658KB 龙书答案 完整性高
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带书签哦,【PS教程】中文版Photoshop.CS6完全自学教程,AdobePhotoshop,简称“PS”,是由AdobeSystems开发和发行的图像处理软件。
Photoshop主要处理以像素所构成的数字图像。
使用其众多的编修与绘图工具,可以有效地进行图片编辑工作。
ps有很多功能,在图像、图形、文字、视频、出版等各方面都有涉及。
2003年,AdobePhotoshop8被更名为AdobePhotoshopCS。
2013年7月,Adobe公司推出了新版本的PhotoshopCC,自此,PhotoshopCS6作为AdobeCS系列的最后一个版本被新的CC系列取代。
2025/11/7 20:36:38 87.71MB Photoshop 带书签 PS教程
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Adobe_Premiere_Pro_CC_官方教程_帮助文档.pdf)
2025/11/7 2:04:03 5.84MB 官方教程
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MELSECDataLinkLibraryReferenceManual-Q80BD-J61BT11N-Q81BD-J61BT11-Q80BD-J71LP21-25-Q80BD-J71LP21S-25-Q81BD-J71LP21-25-Q80BD-J71LP21G-Q80BD-J71BR11-Q80BD-J71GP21-SX-Q80BD-J71GP21S-SX-Q81BD-J71GP21-SX-Q81BD-J71GP21S-SX-Q80BD-J71GF11-T2-Q81BD-J71GF11-T2
2025/10/25 10:52:02 1.93MB MELSEC Data
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8255的8LED显示Proteus,8086主要仿真元件清单:8086,74HC373,74LS240,8255A,7SEG-MPX8-CC-BLUE。
基于8255的8LED显示电子码表设计Proteus仿真8086
2025/7/15 8:44:02 40KB Proteus 8086
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御剑扫描器专业版★新增存活预判(当目标无法连接3次自动撤销任务)★新增首页爬虫(只抓取首页的目录进行二次扫描)★新增文件存储(可以保存扫描结果到指定文位置)★新增跳过大小(可以设定要忽略的页面大小,min-max)★新增GET模式关键字词组过滤(使用GET模式和关闭自定义404才会生效,可以忽略包含指定关键词的页面)★默认参数和值初始化更加科学合理(不合理的设置会导致目标产生CC或者漏报)★优化扫描速度(比1.0提升速度大概5-10倍,通过maxspeed参数控制速度最大值)★优化内存占用(1000/s内存占用10-30M左右)
2025/6/12 14:08:13 2.47MB 爬虫
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手工添加的accessole对象批量导出问题困扰了我很久现在已经解决了希望能够帮助到大家!附有用链接http://dotnet.aspx.cc/file/Removing-OLE-Header-from-images-stored-in-MS-Access-DB-as-OLE-Object.aspx
2025/6/7 4:23:38 41KB access2007 ole对象 图片 c#
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这是斯坦福的著名小兔子模型的点云数据(有ply和PCD格式),里面一共有6个模型。
原数据下载地址http://www.cc.gatech.edu/projects/large_models/
2025/6/6 6:14:08 67.65MB PCD
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这是基于Qt开发的一个2048小游戏,详情可以参考我的博客:ryuzhihao.cc
2025/5/29 0:06:12 17.49MB 2048 qt
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用cc++实现虚拟机...
2025/4/16 9:31:50 4.32MB ajax asp.net c# java
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在日常工作中,钉钉打卡成了我生活中不可或缺的一部分。然而,有时候这个看似简单的任务却给我带来了不少烦恼。 每天早晚,我总是得牢记打开钉钉应用,点击"工作台",再找到"考勤打卡"进行签到。有时候因为工作忙碌,会忘记打卡,导致考勤异常,影响当月的工作评价。而且,由于我使用的是苹果手机,有时候系统更新后,钉钉的某些功能会出现异常,使得打卡变得更加麻烦。 另外,我的家人使用的是安卓手机,他们也经常抱怨钉钉打卡的繁琐。尤其是对于那些不太熟悉手机操作的长辈来说,每次打卡都是一次挑战。他们总是担心自己会操作失误,导致打卡失败。 为了解决这些烦恼,我开始思考是否可以通过编写一个全自动化脚本来实现钉钉打卡。经过一段时间的摸索和学习,我终于成功编写出了一个适用于苹果和安卓系统的钉钉打卡脚本。
2024-04-09 15:03 15KB 钉钉 钉钉打卡