实验一识别无符号数的词法分析器设计实现

1、学院：计算机学院班级：学号：一、实验目的与要求通过编写并上机调试一个词法分析程序，掌握在对程序设计语言的源程序进行扫描的过程中，将其分解成各类单词的词法分析方法。二、实验内容选取无符号数的算术四则运算中的各类单词为识别对象，要求将其中的各个单词识别出来。输入：由无符号数和+，*，/,（,）构成的算术表达式，如1.5E+2100。输出：对识别出的每一单词均单行输出其类别码（无符号数的值暂不要求计算）。单词符号类别码（CLASS）单词值（VALUE）无符号数1数字值+2无值3无值*4无值/5无值(6无值)7无值如1（对应1.5E+2）3(对应)1(对应100)三、程序源代码：#includeusi

2、ngnamespacestd;#defineM101/最多可输入的字符数#defineUNSIGNEDNUMBER1/无符号数#definePLUS2/加号#defineSUBTRACT3/减号#defineMULTIPLY4/乘号#defineDIVIDE5/除号#defineLEFTBRACKET6/左括号#defineRIGHTBRACKET7/右括号classAccidenceAnalysis/定义词法分析器类private:chartestStrM,*p;/私有数据public:AccidenceAnalysis();/构造函数voidInputStr();/输入函数voidOutp

3、ut(inta,char*p1,char*p2);/输出函数intIsAcceptantCharacter(char*p);/判断输入字符是否属于字符集intIsOperator(char*p);/判断字符是否是字符集+,-,*,/,(,)中的字符intIsUnsignedNum(char*p);/判断字符是否是0-9的整数voidAbnormityExamine(chara);voidIdentifyOperator(char*p);/识别字符集+,-,*,/,(,)中的字符voidAssortIdentify();/对输入字符分类识别;AccidenceAnalysis:Accidence

4、Analysis()inti;for(i=0;iM;i+)testStri=0;p=&testStr0;/指针P指向字符数组首元素voidAccidenceAnalysis:InputStr()coutvvt请按要求输入您要分析的语句，所输字符应在要求范围(不超过VVMVV)之内，并按回车键运行：;charch;inti=0;while(ch=cin.get()!=n)testStri=ch;i+;AbnormityExamine(testStr);voidAccidenceAnalysis:AbnormityExamine(chara)intj=0;char*ptr1,*ptr2;ptr1=

5、a;ptr2=a;while(*ptr2!=0)j+;if(!IsAcceptantCharacter(ptr2)coutvvt您输入的第vvjvv个字符vv*ptr2vv不可以被此程序识别！将被跳过.vvendl;ptr2+;continue;else*ptr1=*ptr2;ptr1+;ptr2+;while(ptr1=ptr2)*ptr1=0;ptr1+;voidAccidenceAnalysis:Output(inta,char*p1,char*p2)coutvvt类别码：vvavv单词值：；while(p1=p2)cout*p1；p1+；coutendl；intAccidenceAna

6、lysis:IsOperator(char*p)charch=*p；if(ch=+|ch=-|ch=*|ch=/|ch=(|ch=)return1；elsereturn0；intAccidenceAnalysis:IsUnsignedNum(char*p)charch=*p；if(0=ch&ch=9)return1；elsereturn0；intAccidenceAnalysis:IsAcceptantCharacter(char*p)charch=*p;if(IsOperator(p)|IsUnsignedNum(p)|ch=E|ch=.)return1;elsereturn0;voidAc

7、cidenceAnalysis:IdentifyOperator(char*p)charch=*p;switch(ch)case+:Output(PLUS,p,p);break;case-:Output(SUBTRACT,p,p);break;case*:Output(MULTIPLY,p,p);break;case/:Output(DIVIDE,p,p);break;case(:Output(LEFTBRACKET,p,p);break;case):Output(RIGHTBRACKET,p,p);break;default:break;voidAccidenceAnalysis:Assor

8、tIdentify()while(*p!=0)if(IsOperator(p)IdentifyOperator(p+);continue;elseif(IsUnsignedNum(p)|*p=.)char*p1=p;if(IsUnsignedNum(p)while(IsUnsignedNum(p)p+;if(*p=0)Output(UNSIGNEDNUMBER,p1,-p);p+;continue;elseif(*p=E)p+;if(IsUnsignedNum(p)while(IsUnsignedNum(p)p+;Output(UNSIGNEDNUMBER,p1,-p);p+;continue

9、;elseif(*p=+|*p=-)p+;while(IsUnsignedNum(p)p+;Output(UNSIGNEDNUMBER,p1,-p);p+;continue;elseif(*p=.)p+;while(IsUnsignedNum(p)p+;if(*p=0)Output(UNSIGNEDNUMBER,p1,-p);p+;continue;elseif(*p=E)p+;if(IsUnsignedNum(p)while(IsUnsignedNum(p)p+;Output(UNSIGNEDNUMBER,p1,-p);p+;continue;elseif(*p=+|*p=-)p+;whil

10、e(IsUnsignedNum(p)p+;Output(UNSIGNEDNUMBER,p1,-p);p+;continue;elseOutput(UNSIGNEDNUMBER,p1,-p);p+;continue;elseOutput(UNSIGNEDNUMBER,p1,-p);p+;continue;if(*p=.)p+;if(IsUnsignedNum(p)p+;while(IsUnsignedNum(p)p+;if(*p=0)Output(UNSIGNEDNUMBER,p1,-p);p+;continue;elseif(*p=E)p+;if(IsUnsignedNum(p)while(IsUnsignedNum(p)p+;Output(UNSIGNEDNUMBER,p1,-p);p+;continue;elseif(*p=+|*p=-)p+;while(IsUnsignedNum(p)p+;Output(UNSIGNEDNUMBER,p1,-