词法分析器的设计与实现1

1、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:这在靖宇注册为 数字单堂空方一星f语却为的开程序清单：

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

3、;union", "printf","typedef","const","unsigned","signed","extern","register","static", "volatile","void","if","else","switch","case","for","d

4、o","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 LOCALfreopen("in

5、.txt", "r", stdin);freopen("out.txt", "w", stdout);#endifint 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&

6、#39;&&ch<='Z')|ch='_')(flag=O;q=0;while(ch>='a'&&ch<='z')|(ch>='A'&&ch<='Z')|ch='_'|(ch>='0'&&ch<='9') (if(ch>='0'&&ch<='9')|ch='_') flag

7、=1;bq+=ch; P+； ch=ap;)if(flag=1) (strcpy(,b);wordk+.kind=1;)else if(flag=O) (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>='0'&&ch<

8、='9')|ch='-')int t=p-1;if(at>='0'&&at<='9'|at>='a'&&at<='z'11at>='A'&&at<='Z') (p+;ch=ap;if(ch='-'|ch='=') (b0='-'b1=ch;strcpy(,b);wordk+.kind=5; ch=a+p; else(b

9、0='-'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;elseif(ch='('|ch=')'11ch=''11ch=''|ch=''|ch=''11ch='

10、,'11ch=''11ch=':'11ch='"|ch=巧ch='('| |ch=')'11ch=''11ch=''|ch=''|ch=''|b0=ch;strcpy(,b);wordk+.kind=4;ch=a+p;)else if(ch='%'|ch='A，) (bO=ch;strcpy(,b);wordk+.kind=5; ch=a+p;)else if(ch='+

11、')(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='=') (b0='*'b1=ch;strcpy(,b); wordk+.kind=5;ch=a

12、+p;) else(b0='*'strcpy(,b);wordk+.kind=5;)else if(ch=7')(P+；ch=ap;if(ch=7'|ch='=') (b0=7'b1=ch;strcpy(,b); wordk+.kind=5;ch=a+p;) else(b0=7'strcpy(,b); wordk+.kind=5;)else if(ch='=')(P+；ch=ap;if(ch='=') (b0=b1 ='='

13、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(,b); wordk+.kind=5

14、;)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='=') (b0='!'b1 ='='strcpy(wordk.nam

15、e,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); wordk+.kind=5;ch=a+p;) else(b0='&'strcpy(,b); wordk+.kind=5;)else if(ch='|')(P+；

16、 ch=ap;if(ch='|')(b0=b1=T；strcpy(,b); wordk+.kind=5;ch=a+p;) else(bO=T；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(&

17、quot;(界符,");break;case 5:printf("(运算符,");break;printf("%s)n",);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:7| ift.b