词法分析器的设计与实现(8页).doc
-词法分析器的设计与实现-第 8 页 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： 11060341 学 号： 11060341 姓 名： 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：#include<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","union", "printf","typedef","const","unsigned","signed","extern","register","static", "volatile","void","if","else","switch","case","for","do","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("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')|(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='_') flag=1; bq+=ch; p+; ch=ap; if(flag=1) strcpy(wordk.name,b); wordk+.kind=1; else if(flag=0) if(ch='''|ch='"') strcpy(wordk.name,b); wordk+.kind=2; else if(cmp(b)=1) strcpy(wordk.name,b); wordk+.kind=3; else strcpy(wordk.name,b); wordk+.kind=1; else if(ch>='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(wordk.name,b); wordk+.kind=5; ch=a+p; else b0='-' strcpy(wordk.name,b); wordk+.kind=5; else q=0; bq+=ch; p+; ch=ap; while(ch>='0'&&ch<='9')|ch='.') bq+=ch; p+; ch=ap; strcpy(wordk.name,b); wordk+.kind=2; else if(ch='('|ch=')'|ch=''|ch=''|ch=''|ch=''|ch=','|ch=''|ch=':'|ch='''|ch='"')/ch='('|ch=')'|ch=''|ch=''|ch=''|ch=''| b0=ch; strcpy(wordk.name,b); wordk+.kind=4; ch=a+p; else if(ch='%'|ch='') b0=ch; strcpy(wordk.name,b); wordk+.kind=5; ch=a+p; else if(ch='+') p+; ch=ap; if(ch='+'|ch='=') b0='+' b1=ch; strcpy(wordk.name,b); wordk+.kind=5; ch=a+p; else b0='+' strcpy(wordk.name,b); wordk+.kind=5; else if(ch='*') p+; ch=ap; if(ch='*'|ch='=') b0='*' b1=ch; strcpy(wordk.name,b); wordk+.kind=5; ch=a+p; else b0='*' strcpy(wordk.name,b); wordk+.kind=5; else if(ch='/') p+; ch=ap; if(ch='/'|ch='=') b0='/' b1=ch; strcpy(wordk.name,b); wordk+.kind=5; ch=a+p; else b0='/' strcpy(wordk.name,b); wordk+.kind=5; else if(ch='=') p+; ch=ap; if(ch='=') b0=b1='=' strcpy(wordk.name,b); wordk+.kind=5; ch=a+p; else b0='=' strcpy(wordk.name,b); wordk+.kind=5; else if(ch='>') p+; ch=ap; if(ch='>'|ch='=') b0='>' b1=ch; strcpy(wordk.name,b); wordk+.kind=5; ch=a+p; else b0='>' strcpy(wordk.name,b); wordk+.kind=5; else if(ch='<') p+; ch=ap; if(ch='<'|ch='=') b0='<' b1=ch; strcpy(wordk.name,b); wordk+.kind=5; ch=a+p; else b0='<' strcpy(wordk.name,b); wordk+.kind=5; else if(ch='!') p+; ch=ap; if(ch='=') b0='!' b1='=' strcpy(wordk.name,b); wordk+.kind=5; ch=a+p; else b0='!' strcpy(wordk.name,b); wordk+.kind=5; else if(ch='&') p+; ch=ap; if(ch='&') b0=b1='&' strcpy(wordk.name,b); wordk+.kind=5; ch=a+p; else b0='&' strcpy(wordk.name,b); wordk+.kind=5; else if(ch='|') p+; ch=ap; if(ch='|') b0=b1='|' strcpy(wordk.name,b); wordk+.kind=5; ch=a+p; else b0='|' strcpy(wordk.name,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",wordi.name); int a1=0,a2=0,a3=0,a4=0,a5=0; for(int i=0;i<k;i+) if(wordi.kind=1) a1+; else if(wordi.kind=2) a2+; else if(wordi.kind=3) a3+; else if(wordi.kind=4) a4+; else if(wordi.kind=5) a5+; printf("标识符：%dn常量：%dn关键字：%dn界符：%dn运算符：%dn",a1,a2,a3,a4,a5); return 0;运行结果：
