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1、编译原理第三章 词法分析班级：学号：姓名：schnee目 录1.实验题目和要求32.检测代码分析33. 源代码. 41. 实验题目和要求题目：词法分析程序的设计与实现。实验内容：设计并实现C语言的词法分析程序，要求如下。（1）、可以识别出用C语言编写的源程序中的每个单词符号，并以记号的形式输出每个单词符号。（2）、可以识别并读取源程序中的注释。（3）、可以统计源程序汇总的语句行数、单词个数和字符个数，其中标点和空格不计算为单词，并输出统计结果（4）、检查源程序中存在的错误，并可以报告错误所在的行列位置。（5）、发现源程序中存在的错误后，进行适当的恢复，使词法分析可以继续进行，通过一次词法分析处
2、理，可以检查并报告源程序中存在的所有错误。实验要求：方法1：采用C/C+作为实现语言，手工编写词法分析程序。方法2：通过编写LEX源程序，利用LEX软件工具自动生成词法分析程序。2. 检测代码分析1、 Hello World简单程序输入：2、 较复杂程序输入：3. 异常程序输入检测三， 源代码#include #include #include #include #include #include #include #include #include #include using namespace std;const int FILENAME=105;const int MAXBUF=82;
3、const int L_END=40;const int R_END=81;const int START=0; /开始指针vector Key; /C保留的关键字表class funtion /词法分析结构public:/变量声明char filenameFILENAME; /需要词法分析的代码文件名ifstream f_in;char bufferMAXBUF; /输入缓冲区int l_end, r_end, forward; /左半区终点，右半区终点，前进指针，bool l_has, r_has; /辅助标记位，表示是否已经填充过缓冲区vector Id; /标识符表char C; /当
4、前读入的字符int linenum, wordnum, charnum; /行数，单词数，字符数string curword; /存放当前的字符串/函数声明void get_char(); /从输入缓冲区读一个字符，放入C中，forward指向下一个void get_nbc(); /检查当前字符是否为空字符，反复调用直到非空void retract(); /向前指针后退一位void initial(); /初始化要词法分析的文件void fillBuffer(int pos); /填充缓冲区，0表示左,1表示右void analyzer(); /词法分析void token_table();
5、/以记号的形式输出每个单词符号void note_print(); /识别并读取源程序中的注释void count_number(); /统计源程序汇总的语句行数、单词个数和字符个数void error_report(); /检查并报告源程序中存在的所有错误void solve(char* file); /主调用函数;void welcome()printf(n*n);printf( * Welcome to use LexicalAnalyzer *n);printf( * By schnee BUPT Date: 2011/20/10 *n);printf( *nnn);void init
6、Key()Key.clear();Key.push_back(auto); Key.push_back(break); Key.push_back(case); Key.push_back(char); Key.push_back(const); Key.push_back(continue);Key.push_back(default); Key.push_back(do); Key.push_back(double); Key.push_back(else); Key.push_back(enum); Key.push_back(extern); Key.push_back(float);
7、 Key.push_back(for); Key.push_back(goto); Key.push_back(if); Key.push_back(int); Key.push_back(long); Key.push_back(register);Key.push_back(return); Key.push_back(short); Key.push_back(signed); Key.push_back(static); Key.push_back(sizeof); Key.push_back(struct); Key.push_back(switch); Key.push_back(
8、typedef); Key.push_back(union); Key.push_back(unsigned);Key.push_back(void); Key.push_back(volatile);Key.push_back(while);void funtion:get_char()C=bufferforward;if(C=EOF)return ; /结束if(C=n)linenum+; /统计行数和字符数else if(isalnum(C) charnum+;forward+;if(bufferforward=EOF)if(forward=l_end)fillBuffer(1);for
9、ward+;else if(forward=r_end)fillBuffer(0);forward=START;void funtion:get_nbc()while(C= | C=n | C=t | C=0)get_char();void funtion:initial(char* file)Id.clear(); /清空标识符表l_end=L_END;r_end=R_END; /初始化缓冲区forward=0;l_has=r_has=false;bufferl_end=bufferr_end=EOF;fillBuffer(0);linenum=wordnum=charnum=0; /初始化
10、行数，单词数，字符数void funtion:fillBuffer(int pos)if(pos=0)/填充缓冲区的左半边if(l_has=false)fin.read(buffer, l_end);if(fin.gcount()!=l_end)bufferfin.gcount()=EOF;else l_has=false;else /填充缓冲区的右半边if(r_has=false)fin.read(buffer+l_end+1, l_end);if(fin.gcount()!=l_end)bufferfin.gcount()+l_end+1=EOF;else r_has=false;void
11、 funtion:retract()if(forward=0)l_has=true; /表示已经读取过文件，避免下次再次读取forward=l_end-1;elseforward-;if(forward=l_end)r_add=true;forward-;void funtion:analyzer()FILE *token_file, *note_file, *count_file, *error_file;token_file=fopen(token_file.txt, w);note_file=fopen(note_file.txt, w);count_file=fopen(count_f
12、ile.txt, w);error_file=fopen(error_file.txt, w);int i;curword.clear();get_char();get_nbc();if(C=EOF)return false;if(isalpha(C) | C=_)/关键字和标识符的处理，以字母或下划线开头curword.clear();while(isalnum(C) | C=_)curword.push_back(C);get_char();retract();wordnum+;Id.push_back(curword);for(i=0; iKey.size(); i+)if(Keyi=c
13、urword)break;/输出每一个单词的标识符if(iKey.size() /关键字fprintf(token_file, %8d-%20s %sn, wordnum, KEY WORD, curword);elsefprintf(token_file, %8d-%20s %sn, wordnum, Identifier, curword);else if(isdigit(C)/无符号数的处理curword.clear();while(isdigit(C)curword.push_back(C);get_char();if(C=. | C=E | C=e)/处理小数和指数形式curword
14、.push_back(C);get_char();while(isdigit()curword.push_back(C);get_char();retract();wordnum+;Id.push_back(curword);fprintf(token_file, %8d-%20s %sn, wordnum, Unsigned Number, curword);else if(C=#)/过滤掉以#开头的预处理fprintf(note_file, preproccess Line %d : , linenum);get_char();fprintf(note_file, %c, C);while
15、(C!=n)get_char(); fprintf(note_file, %c, C);fprintf(note_file, %c, C);else if(C=)/内的句子当成整个串保存起来curword.clear();get_char();while(C!=)curword.push_back(C);get_char();fprintf(token_file, *string in -%sn, curword);else if(C=/)get_char();if(C=/)/过滤掉/开头的行注释fprintf(note_file, single-line note Line %d : , l
16、inenum);get_char();curword.clear();while(C!=n)curword.push_back(C);get_char();fprintf(note_file, %sn, curword);else if(C=*)/过滤掉/*/之间的段注释fprintf(note_file, paragraph note Line %d : , linenum);get_char();while(true)while(C!=/) fprintf(note_file, %c, C); get_char();get_char();if(C=*)fprintf(note_file,
17、nto Line %dn, linenum);break;fprintf(note_file, %c, C);else if(C=)fprintf(token_file, *ASSIGN-OP, DIVn);elsefprintf(token_file, *CAL-OP, DIVn);retract(); /处理各种比较，赋值，运算符号else if(C=)get_char();if(C=)fprintf(token_file, *RELOP, GEn);elsefprintf(token_file, *RELOP, GTn);retract();else if(C=)get_char();i
18、f(C=)fprintf(token_file, *RELOP, EQn);elsefprintf(token_file, *ASSIGN-OP, EASYn);retract();else if(C=+)get_char();if(C=)fprintf(token_file, *ASSIGN-OP, ADDn);elsefprintf(token_file, *CAL-OP, ADDn);retract();else if(C=-)get_char();if(C=)fprintf(token_file, *ASSIGN-OP, SUBn);elsefprintf(token_file, *C
19、AL-OP, SUBn);retract();else if(C=*)get_char();if(C=)fprintf(token_file, *ASSIGN-OP, MULn);elsefprintf(token_file, *CAL-OP, MULn);retract();else if(C=!)get_char();if(C=)fprintf(token_file, *RELOP, UEn);else if(!isalpha(C) & C!=_)fprintf(error_file, Line %d: error: ! was illegal char n, linenum);else
20、if(C=: | C=( | C=) | C=; | C= | C= | C=,)fprintf(token_file, *Other char-%cn, C);elsefprintf(error_file, Line %d: error: %c was illegal char n, linenum, C);fprintf(count_file, The Line number is %dn, linenum);fprintf(count_file, The word number is %dn, wordnum);fprintf(count_file, The char number is
21、 %dn, charnum);fclose(token_file);fclose(note_file);fclose(count_file);fclose(error_file);void funtion:token_table()fin.open(token_file.txt);printf(The token_table is as following:n);char str1;while(1)fin.read(str, 1);if(str0!=EOF)printf(%c, str0);void funtion:note_print()fin.open(note_file.txt);pri
22、ntf(The note is as following:n);char str1;while(1)fin.read(str, 1);if(str0!=EOF)printf(%c, str0);void funtion:count_number()fin.open(count_file.txt);printf(The count result is as following:n);char str1;while(1)fin.read(str, 1);if(str0!=EOF)printf(%c, str0);void funtion:error_report()fin.open(error_f
23、ile.txt);printf(The error report is as following:n);char str1;while(1)fin.read(str, 1);if(str0!=EOF)printf(%c, str0);void funtion:solve(char* file)filename=file;fin.open(filename);intitial();analyzer();int choice;printf(* We have analyzed %s n);printf(*0: To endn);printf(*1: To get the token tablen)
24、;printf(*2: To get the note part of filen);printf(*4: To report all the error of the filen);printf(*3: To get the line num, word num and charter numnn);while(1)printf(*please input your choice: );scanf(%d, &choice);if(choice=0)break;if(choice=1)token_table();else if(choice=2)note_print();else if(cho
25、ice=3)count_number();else error_report();printf(n);void LexicalAnaylzer(char* file)funtion test;test.solve(file);int main()welcome();initKey();char fileFILENAME;while(1)printf(nDo you want to continue? (YES or NO): );scanf(%s, file);if(strcmp(file, NO)=0)printf(Thanks for your use! GoodBye next time!nn);break;printf(Please type your C file name(for example: a.cpp): );scanf(%s, file);LexicalAnalyzer(file);return 0;