词法分析词法分析报告.doc

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1、词法分析报告姓名：李思婕学号：912106840301班级：91210658011.程序目的：1.巩固对词法分析的基本功能和原理的认识。2.能够应用自动机的知识进行词法分析。3.理解并处理词法分析中的异常和错误。2.程序设计分析：该程序可分为如下几步：（1）打开fin.txt文件（2）从fin.txt逐个字符读入，若遇到空格则判断为一个标示符（3）将读入的标示符与关键字进行比较，若是关键字则识别（4）若不是关键字则默认为自定义标示符（5）将分析结果输出到自定义的TXT文件内本程序自行规定：(1)关键字"program","begin","end","var",

2、"integer","real","for","if","then","else","do","while","array","procedure","function","of"，"boolean"，"const"，"div"，"mod"，"and"，"or"(2)运算符："+","-","*","/","="(3)界符："{","}","[","]",";",",",".","(",")",":"(4)其他标记如字符串，表示以字母开头的标识符。(5)空格、回车、换行符跳过3.程序流程图4.关键部分程序voidanalyse(FILE*fpin,FILE*f

3、pout){chararr[MAXBUF];/*输入缓冲区，存放一个单词符号*/intj=0;while((ch=fgetc(fpin))!=EOF){if(ch==''

4、

5、ch=='t'){}/*碰到空格、tab则跳过*/elseif(ch==''){Line_NO++;}/*************************字符串的处理****************************/elseif(IsLetter(ch)){while(IsLetter(ch)

6、IsDigit(ch)){if((ch<='Z')&&(ch>='A'))ch=c

7、h+32;/*忽略大小写*/arr[j]=ch;j++;ch=fgetc(fpin);}fseek(fpin,-1L,SEEK_CUR);/*输入指针回退一个字符*/arr[j]='';j=0;if(se_res(arr)){/*如果是关键字*/fprintf(fpout,"%stt%d",arr,se_res(arr));}elsefprintf(fpout,"%stt%d",arr,1);/*普通标识符*//*************************数字的处理****************************/}elsei

8、f(IsDigit(ch)){while(IsDigit(ch)){arr[j]=ch;j++;ch=fgetc(fpin);}fseek(fpin,-1L,SEEK_CUR);arr[j]='';j=0;fprintf(fpout,"%stt%d",arr,2);/*无符号整数*/}elseswitch(ch){case'+':fprintf(fpout,"%stt%d","+",41);break;case'-':fprintf(fpout,"%stt%d","-",42);break;case'*':fprintf(fpout

9、,"%stt%d","*",43);break;case'(':fprintf(fpout,"%stt%d","(",25);break;case')':fprintf(fpout,"%stt%d",")",26);break;case'[':fprintf(fpout,"%stt%d","[",27);break;case']':fprintf(fpout,"%stt%d","]",28);break;case';':fprintf(fpout,"%stt%d",";",36);break;case'=':fp

10、rintf(fpout,"%stt%d","=",38);break;case'.':fprintf(fpout,"%stt%d",".",39);break;case',':fprintf(fpout,"%stt%d",",",40);break;case':':{ch=fgetc(fpin);if(ch=='=')fprintf(fpout,"%stt%d",":=",29);else{fprintf(fpout,"%stt%d",":",30);fseek(fpin,-1L,SEEK_CUR);}}break;ca

11、se'>':{ch=fgetc(fpi