编译原理实验报告(一)----词法分析程序(共11页).doc

精选优质文档-倾情为你奉上 编译原理实验报告（一） 词法分析程序【目的要求】 通过设计编制调试一个具体的词法分析程序，加深对词法分析原理的理解。并掌握在对程序设计语言源程序进行扫描过程中将其分解为各类单词的词法分析方法。 【题目分析】本实验以用户指定的想编译的以C语言编写的文件作为词法分析程序的输入数据。在进行词法分析中，先自文件头开始以行为单位扫描程序，将该行的字符读入预先设定的一个数组缓冲区中，然后对该数组的字符逐词分割，进行词法分析，将每个词分割成关键字、标识符、常量和运算符四种词种，最终产生四个相对应的表，即关键字表、标识符表、常量表和运算符表，它们以文件的形式进行存储。除此之外，还产生一个编译后的文件，它指定了每个词在四个表中的位置。【实验过程】下面就词法分析程序中的文件和主要变量进行说明： 文件： cpile.c 主程序文件 key.txt 关键字文件 operation.txt 运算符文件 id.txt 标识符文件 const.txt 常量文件 after_com.txt 编译后产生的文件 主要变量： FILE *sfp,*nfp,*ifp,*kfp,*cfp,*pfp; char ib5020 标识符表（动态生成）char cb5010 常量表（动态生成） char kb4410 关键字表（预先定义好的）char pb365 运算符表（预先定义好的） 主要的子函数名： int number(char s,int i); 数字处理函数 int letter(char s,int i); 字符处理函数 int operation(char s,int i); 运算符处理函数 void seti (char s); 标识符建立函数void setc (char s); 常量建立函数 void cfile(char s1, char s2,int m); 将词和词所在表中位置写入编译后文件 void error1(char s); 字符处理出错报告 void error2(char s); 标识符处理出错报告 void error3(char s); 运算符处理出错报告void openall(); 打开所有文件void writeall(); 将四个表写入文件void closeall(); 关闭所有文件下面简要分析一下词法分析程序的运行流程：能否打开所要编译的C语言文件 否 报错 能判断当前字符是否是文件结束符是结束从源程序中读入一行到数组缓冲区否判断当前字符是否是n是否判断当前字符是否是字母是转关键字和标识符处理否判断当前字符是否是数字是转数字处理否判断当前字符是否是运算符是转运算符处理否【程序调试】现有源程序a.c清单如下： #include <stdio.h>int main(int argc, char *argv)char ch; int i; ch='a' ch=ch+32 ; i=ch; printf("%d id %cn",i,ch);/*打印*/ return 0; 运行词法分析程序后，显示如下结果：after_com.txt文件：#p-2includei-0<p-14stdio.hi-1>p-16intk-2maini-2(p-7intk-2argci-3,p-6chark-0*p-9argvi-4p-18p-21)p-8p-23chark-0chi-5;p-13intk-2ii-6;p-13chi-5=p-15'p-19ai-7'p-19;p-13chi-5=p-15chi-5+p-1032c-0;p-13ii-6=p-15chi-5;p-13printfk-33(p-7"p-1%p-4di-8idi-9%p-4ci-10p-20ni-11"p-1,p-6ii-6,p-6chi-5)p-8;p-13returnk-280c-1;p-13p-25key.txt 关键字文件：0 char1 short2 int3 unsigned4 long5 float6 double7 struct8 union9 void10 enum11 signed12 const13 volatile14 typedef15 auto16 register17 static18 extem19 break20 case21 continue22 default23 do24 else25 for26 goto27 if28 return29 switch30 while31 sizeof32 txt33 printf34 FILE35 fopen36 NULL37 fclose38 exit39 r40 read41 close42 w43 fprintf id.txt 标识符文件：0 include1 stdio.h2 main3 argc4 argv5 ch6 i7 a8 d9 id10 c11 noperation.txt 运算符文件：0 !1 "2 #3 $4 %5 &6 ,7 (8 )9 *10 +11 -12 :13 ;14 <15 =16 >17 ?18 19 '20 21 22 .23 24 |25 26 !=27 >=28 <=29 =30 +31 -32 &&33 /*34 */ const.txt 常量文件：0 321 0结果完全正确。词法分析程序如下：#include <stdio.h>#include <string.h>#include <stdlib.h>#include <ctype.h>#define SIZE 256#define null 0int line=0,error=0,mark1=0,mark2=0; char *sname;FILE *sfp,*nfp,*ifp,*kfp,*cfp,*pfp;/*-*/ char ib5020; char cb5010; char kb4410="char","short","int","unsigned","long","float","double","struct","union","void", "enum","signed","const","volatile","typedef","auto","register","static","extem", "break","case","continue","default","do","else","for","goto", "if","return","switch","while","sizeof","txt","printf","FILE","fopen","NULL", "fclose","exit","r","read","close","w","fprintf" char pb365="!",""","#","$","%","&",",","(",")","*","+","-",":","","<","=",">","?","","'", "","",".","","|","","!=",">=","<=","=","+","-","&&","/*","*/"/*-定义了四个二元数组存放四个表-*/int main(int argc, char *argv) char sbuffSIZE; char nbuffSIZE; int i;/*-*/ int number(char s,int i); int letter(char s,int i); int operation(char s,int i); void seti (char s); void setc (char s); void cfile(char s1, char s2,int m); void error2(char s); void error1(char s);void error3(char s);void openall();void writeall();void closeall();/*-*/ if(argc!=2) printf("Please input the file you want to compile:n"); exit(1); else sname=argv1; sfp=fopen(argv1,"r"); openall(); i=0; while(i<50 ) strcpy(ibi," "); strcpy(cbi," "); i+; /*-*/ while(fgets(sbuff,SIZE,sfp) i=0;line+; /*以行的方式读取源代码进行编译*/while(sbuffi!='n') if(isalpha(sbuffi) /* 处理关键字和标识符 */ i=letter(sbuff,i); else if(isdigit(sbuffi) i=number(sbuff,i); /* 处理数字常量 */ else i=operation(sbuff,i); /* 处理运算符 */fputc('n',nfp); /*-*/ if(error)printf("!There are %d errors.",error); /* 最后错误个数报告 */elseprintf("Success to compile the file."); writeall();closeall(); return 0;/*$*/void openall() /* 打开所有必需的文件 */ kfp=fopen("key.txt","w+"); /* 打开关键字表 */ pfp=fopen("operation.txt","w+"); /* 打开运算符表 */ cfp=fopen("const.txt","w+"); /* 打开常量文件 */ ifp=fopen("id.txt","w+"); /* 打开标识符文件 */ nfp=fopen("after_com.txt","w+"); /* 打开编译后会产生的文件 */ if(kfp=NULL | cfp=NULL | ifp=NULL | pfp=NULL | nfp=NULL) printf("Cannot open these files"); /* 打开文件有错，退出程序 */ exit(0); /*-*/void writeall() int m=0; while (m<36&&pbm!=" ") fprintf(pfp,"%d%s%sn", m," ",pbm);m+; m=0; while (m<44&&kbm!=" ") fprintf(kfp,"%d%s%sn", m," ",kbm);m+; m=0; while (m<mark2&&cbm!=" ") fprintf(cfp,"%d%s%sn", m," ",cbm);m+; m=0; while (m<mark1&&ibm!=" ") fprintf(ifp,"%d%s%sn", m," ",ibm);m+; /*-*/void closeall() /* 关闭所有文件 */ fclose(kfp); fclose(pfp); fclose(cfp); fclose(ifp); fclose(nfp);/*$*/int letter(char sbuff,int i)char str10; void cfile(char s1, char s2,int m); void seti (char s); void setc (char s); int m=0,n=0; strn=sbuffi; while(isalnum(sbuffi)|sbuffi='.') strn+=sbuffi+; strn='0' while (m<44&&(strcmp(str,kbm)!=0) m+; if (m<44) cfile(str,"k",m); else m=0; while (m<50&&(strcmp(str,ibm)!=0) m+; if (m<50) cfile (str,"i",m); else seti(str); return i;/*-*/int number(char sbuff,int i)char s2,str10; void cfile(char s1, char s2,int m);void seti (char s);void setc (char s); void error2(char s); void error1(char s);int m=0,n=0;strn=sbuffi;i+;n+; if(sbuffi='.') strn=sbuffi; if (sbuffi='E' | sbuffi='e') && (sbuffi+1='+' | sbuffi+1='-' |isdigit(sbuffi+1) strn=sbuffi;strn+=sbuffi+; while (isdigit(sbuffi) strn+=sbuffi+; /*对可能出现的十进制数的处理*/ strn+='0' while (m<50&&(strcmp(str,cbm)!=0) m+; if (isalpha(sbuffi) error2(str); else if (m<50) cfile(str,"c",m); else setc(str);return i;/*-*/int operation(char sbuff,int i) void error3(char s); void cfile(char s1, char s2,int m); void setc (char s); int k=0,m=0;char s4; if (sbuffi='/'&&sbuffi+1='*') i=i+2; while (!(sbuffi='*'&&sbuffi+1='/') i+; i=i+2; /*若为注释则跳过*/ else if(sbuffi=' ') while(sbuffi=' ') i+; else sk=sbuffi; while (k<3) sk+=sbuffi+; while (k>=0) sk='0' m=0; while (m<36&&(strcmp(s,pbm)!=0) m+; if (m<36) cfile(s,"p",m); break; else k-;i-; if (k=-1) i+; error3(s); return i;/*-*/void cfile(char s1, char s2,int m) fprintf(nfp,"%s%s-%dn",s1,s2,m);return;void seti (char s)void cfile(char s1, char s2,int m); strcpy(ibmark1,s); cfile(s,"i",mark1); mark1+; return ;void setc (char s)void cfile(char s1, char s2,int m); strcpy(cbmark2,s); cfile(s,"c",mark2); mark2+; return ;/*-*/void error1 (char s) error+;printf("line %d:%s is an illegal letter.n",line,s); return ;void error2(char s) error+;printf("line %d:%s is an illegal word.n",line,s); return ;void error3(char s) error+; printf("line %d:%s is an illegal operation.n",line,s); return ; /*-*/【编程体会】A编写程序之前应该要有一个整体的规划，然后在考虑细节问题，不断地发现问题，修改程序，使之精益求精。B. 通过本实验，我更加深了对文件操作的理解，能够较好的掌握文件操作的基本要领。C. 应该培养良好的程序设计风格。 专心-专注-专业