编译原理实验词法分析器

1、#include "stdio.h"#include "string.h"#include "stdlib.h"char key89="if","int","for","while","do","return","break","continue" /保留字char operater103="+","-","*",&q

2、uot;/","=",">","<",">+","<+","!=" /运算符char delimiter62=",","","","","(",")" /分隔符char real102="1","2","3","4","5",

3、"6","7","8","9","."int main()int i=0;void part();char name10,source100;printf("请输入文件名:n");scanf("%s",&name);FILE *fp; /文件操作if(fp=fopen(name,"r")=NULL) /打开文件printf("File open error!n");exit(0);while(!feof(fp

4、)sourcei=fgetc(fp);i+;sourcei-1='0'printf("分离结果为:n");part();return 0;void part()int i=0;int j,k,flag,flag1; /flag为是否已判断的标志 flag1为常量的标志char source100;char midest50; /中间数组，临时存放分离的单词while(sourcei!='0') /逐个读入字符组成单独的单词j=0;flag=0;flag1=0;domidestj=sourcei;i+;j+; /当不是分隔符和运算符和其他定义的

5、符号时 继续循环while(sourcei!=' '&&sourcei!='+'&&sourcei!='-'&&sourcei!='*'&&sourcei!='/'&&sourcei!='='&&sourcei!='>'&&sourcei!='<'&&sourcei!='>+'&&source

6、i!='<+'&&sourcei!='!='&&sourcei!=','&&sourcei!=''&&sourcei!=''&&sourcei!=''&&sourcei!='('&&sourcei!=')');midestj='0' /退出循环时把最后一个存储单元定义为0作为字符串的结束符 /判断midest数组中的内容 /判断是否为保

7、留字for(k=0;k<8;k+)if(strcmp(midest,keyk)=0)printf("(%s,1)n",midest); /输出保留字flag=1;break; if(flag=0) /判断是否为常量for(k=0;midestk!='0'k+)if(midestk<48 | midestk>57 )flag1=1;break;if(flag1=0)printf("(%s,3)n",midest);/输出常量flag=1;if(flag=0) /判断是否输入错误，如果无错误，则是标识符if(midest0&

8、gt;=48 && midest0<=57)printf("%s输入错误!n",midest);elsefor(k=1;midestk!='0'k+)if(midestk>='a' && midestk<='z')|(midestk>='A' && midestk<='Z')|(midestk>='1' && midestk<='9')|(midestk=&#

9、39;_')|(midestk='#')|(midestk='.')flag=0;elseflag=1;break;if(flag=0)printf("(%s,2)n",midest);elseprintf("%s输入错误!n",midest);if(sourcei=' ')i+;if(sourcei='+'|sourcei='-'|sourcei='*'|sourcei!='/'|sourcei='='|sourcei

10、='>'|sourcei='<'|sourcei='>+'|sourcei='<+'&&sourcei='!='|sourcei=','|sourcei=''|sourcei=''|sourcei=''|sourcei='('|sourcei=')')j=0;flag=0;midestj=sourcei;midestj+1='0'if(flag=0)for(k=0;k<10;k+)if(strcmp(midest,operaterk)=0) /看是不是运算符if(midestj='>'|midestj='<') /如果是运算符 再判断是不是<号或>号 如果是 再查看后面有没有=号 if(sourcei+1='=')midestj+1=sourcei+1; /如果有=号 就让=跟在>或<号后面输出midestj+2='0'i+;printf("(