词法分析器的设计与实现

1、精选优质文档-倾情为你奉上 编译原理课程实验报告 实验题目： 某种简单程序语言的词法分析器的设计 与实现 专 业： 计算机科学与技术 班 级： 学 号： 姓 名： 专心-专注-专业实验目的：设计一个词法分析程序，理解词法分析器实现的原理，掌握程序设计语言中的各类单词的词法分析方法，加深对词法分析原理的理解。实验任务：词法分析是从左向右扫描每行源程序的符号，拼成单词，换成统一的二元式 (单词种别，单词符号的属性值)表示。对给定的程序通过词法分析器识别一个个单词符号，并以二元式(单词种别，单词符号的属性值)显示，本程序则是通过对给定程序段分析后以单词符号和文字提示显示）实验流程：程序清单：#inc

2、lude<iostream>#include<cstdio>#include<cstring>using namespace std;int k=0;struct word char name10; int kind; word1000;char key3510= "scanf","short","int","long","float","double","char","struct","u

3、nion", "printf","typedef","const","unsigned","signed","extern","register","static", "volatile","void","if","else","switch","case","for","do&

4、quot;,"while","goto", "continue","break","default","sizeof","return","include","bool" ;bool cmp(char a) int i; for(int k=0; k<35; k+) if(strcmp(a,keyk)=0) return 1; return 0;int main() #ifdef LOCAL freopen(&

5、quot;in.txt", "r", stdin); freopen("out.txt", "w", stdout); #endif int p,q,flag; char a1000,b10,ch; while(gets(a) p=0; int len=strlen(a); while(p<len) ch=ap; memset(b,0,sizeof(b); while(ch=' ') p+; ch=ap; if(ch>='a'&&ch<='z'

6、)|(ch>='A'&&ch<='Z')|ch='_') flag=0; q=0; while(ch>='a'&&ch<='z')|(ch>='A'&&ch<='Z')|ch='_'|(ch>='0'&&ch<='9') if(ch>='0'&&ch<='9')|ch

7、='_') flag=1; bq+=ch; p+; ch=ap; if(flag=1) strcpy(,b); wordk+.kind=1; else if(flag=0) if(ch='''|ch='"') strcpy(,b); wordk+.kind=2; else if(cmp(b)=1) strcpy(,b); wordk+.kind=3; else strcpy(,b); wordk+.kind=1; else if(ch>=

8、9;0'&&ch<='9')|ch='-') int t=p-1; if(at>='0'&&at<='9'|at>='a'&&at<='z'|at>='A'&&at<='Z') p+; ch=ap; if(ch='-'|ch='=') b0='-' b1=ch; strcpy(,b); w

9、ordk+.kind=5; ch=a+p; else b0='-' strcpy(,b); wordk+.kind=5; else q=0; bq+=ch; p+; ch=ap; while(ch>='0'&&ch<='9')|ch='.') bq+=ch; p+; ch=ap; strcpy(,b); wordk+.kind=2; else if(ch='('|ch=')'|ch=''|ch=''|

10、ch=''|ch=''|ch=','|ch=''|ch=':'|ch='''|ch='"')/ch='('|ch=')'|ch=''|ch=''|ch=''|ch=''| b0=ch; strcpy(,b); wordk+.kind=4; ch=a+p; else if(ch='%'|ch='') b0=ch; strc

11、py(,b); wordk+.kind=5; ch=a+p; else if(ch='+') p+; ch=ap; if(ch='+'|ch='=') b0='+' b1=ch; strcpy(,b); wordk+.kind=5; ch=a+p; else b0='+' strcpy(,b); wordk+.kind=5; else if(ch='*') p+; ch=ap; if(ch='*'|ch='='

12、;) b0='*' b1=ch; strcpy(,b); wordk+.kind=5; ch=a+p; else b0='*' strcpy(,b); wordk+.kind=5; else if(ch='/') p+; ch=ap; if(ch='/'|ch='=') b0='/' b1=ch; strcpy(,b); wordk+.kind=5; ch=a+p; else b0='/' strcpy(

13、,b); wordk+.kind=5; else if(ch='=') p+; ch=ap; if(ch='=') b0=b1='=' strcpy(,b); wordk+.kind=5; ch=a+p; else b0='=' strcpy(,b); wordk+.kind=5; else if(ch='>') p+; ch=ap; if(ch='>'|ch='=') b0='>' b1=ch; strcpy

14、(,b); wordk+.kind=5; ch=a+p; else b0='>' strcpy(,b); wordk+.kind=5; else if(ch='<') p+; ch=ap; if(ch='<'|ch='=') b0='<' b1=ch; strcpy(,b); wordk+.kind=5; ch=a+p; else b0='<' strcpy(,b); wordk+.kind

15、=5; else if(ch='!') p+; ch=ap; if(ch='=') b0='!' b1='=' strcpy(,b); wordk+.kind=5; ch=a+p; else b0='!' strcpy(,b); wordk+.kind=5; else if(ch='&') p+; ch=ap; if(ch='&') b0=b1='&' strcpy(,b); word

16、k+.kind=5; ch=a+p; else b0='&' strcpy(,b); wordk+.kind=5; else if(ch='|') p+; ch=ap; if(ch='|') b0=b1='|' strcpy(,b); wordk+.kind=5; ch=a+p; else b0='|' strcpy(,b); wordk+.kind=5; for(int i=0; i<k; i+) switch(wordi.kind) case 1: printf("(标识符,"); break; case 2: printf("(常量,"); break; case 3: printf("(关键字,"); break; case 4: printf("(界符,"); break; case 5: printf("(运算符,"); break; printf("%s)n",); in