词法分析器.doc

#includeusing namespace std;#define M 101 /最多可输入的字符数#define UNSIGNEDNUMBER 1 /无符号数#define PLUS 2 /加号#define SUBTRACT 3/减号#define MULTIPLY 4/乘号#define DIVIDE 5/除号#define LEFTBRACKET 6/左括号#define RIGHTBRACKET 7/右括号class AccidenceAnalysis /定义词法分析器类private:char testStrM,*p;/私有数据public:AccidenceAnalysis();/构造函数void InputStr();/输入函数void Output(int a,char *p1,char *p2);/输出函数int IsAcceptantCharacter(char *p);/判断输入字符是否属于字符集int IsOperator(char *p);/判断字符是否是字符集+,-,*,/,(,)中的字符int IsUnsignedNum(char *p);/判断字符是否是0-9的整数void AbnormityExamine(char a);void IdentifyOperator(char *p);/识别字符集+,-,*,/,(,)中的字符void AssortIdentify();/对输入字符分类识别;AccidenceAnalysis:AccidenceAnalysis()int i;for(i=0;iM;i+)testStri=0;p=&testStr0; /指针P指向字符数组首元素void AccidenceAnalysis:InputStr()coutt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M)之内，并按回车键运行：;char ch;int i=0;while(ch=cin.get()!=n)testStri=ch;i+;AbnormityExamine(testStr);void AccidenceAnalysis:AbnormityExamine(char a)int j=0;char *ptr1,*ptr2;ptr1=a;ptr2=a;while(*ptr2!=0)j+;if(!IsAcceptantCharacter(ptr2)coutt您输入的第j个字符 *ptr2 不可以被此程序识别！ 将被跳过.endl;ptr2+;continue;else*ptr1=*ptr2;ptr1+;ptr2+;while(ptr1=ptr2)*ptr1=0;ptr1+;void AccidenceAnalysis:Output(int a,char *p1,char *p2)coutt类别码：a 单词值：;while(p1=p2)cout*p1;p1+;coutendl;int AccidenceAnalysis:IsOperator(char *p)char ch=*p;if(ch=+|ch=-|ch=*|ch=/|ch=(|ch=)return 1;elsereturn 0;int AccidenceAnalysis:IsUnsignedNum(char *p)char ch=*p;if(0=ch&ch=9)return 1;elsereturn 0;int AccidenceAnalysis:IsAcceptantCharacter(char *p)char ch=*p;if(IsOperator(p)|IsUnsignedNum(p)|ch=E|ch=.)return 1;else return 0;void AccidenceAnalysis:IdentifyOperator(char *p)char ch=*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; void AccidenceAnalysis:AssortIdentify() while(*p!=0) if(IsOperator(p) IdentifyOperator(p+); continue; else if(IsUnsignedNum(p)|*p=.) char *p1=p;if(IsUnsignedNum(p)while(IsUnsignedNum(p)p+;if(*p=0)Output(UNSIGNEDNUMBER,p1,-p);p+;continue;else if(*p=E)p+;if(IsUnsignedNum(p)while(IsUnsignedNum(p)p+;Output(UNSIGNEDNUMBER,p1,-p);p+;continue;else if(*p=+|*p=-)p+;while(IsUnsignedNum(p)p+;Output(UNSIGNEDNUMBER,p1,-p);p+;continue;else if(*p=.)p+;while(IsUnsignedNum(p)p+;if(*p=0)Output(UNSIGNEDNUMBER,p1,-p);p+;continue;else if(*p=E)p+;if(IsUnsignedNum(p)while(IsUnsignedNum(p)p+;Output(UNSIGNEDNUMBER,p1,-p);p+;continue;else if(*p=+|*p=-)p+;while(IsUnsignedNum(p)p+;Output(UNSIGNEDNUMBER,p1,-p);p+;continue;elseOutput(UNSIGNEDNUMBER,p1,-p);p+;continue;else Output(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;else if(*p=E)p+;if(IsUnsignedNum(p)while(IsUnsignedNum(p)p+;Output(UNSIGNEDNUMBER,p1,-p);p+;continue;else if(*p=+|*p=-)p+;while(IsUnsignedNum(p)p+;Output(UNSIGNEDNUMBER,p1,-p);p+;continue;else Output(UNSIGNEDNUMBER,p1,-p);p+;continue; coutendl;