词法分析程序新

  1 #include<stdio.h>
  2 #define MAX 100
  3 char ch,zifu[MAX],linshi[15];
  4 int zhongbie,p;/*zhongbie代表字符种别,p代表数组zifi的下标位置*/
  5 void cwh();
  6 main()
  7 {
  8     p=0;
  9     gets(zifu);
 10     do{
 11         cwh();
 12         if(zhongbie==-1)
 13             continue;
 14         printf("<%d,",zhongbie);
 15         printf("%s>\n",linshi);
 16     }while(zhongbie!=-1);
 17 }
 18 void cwh()
 19 {
 20     int i,m;/*m用于记录linshi的下标*/
 21     char *guanjianzi[6]={"begin","if","then","while","do","end"};/*char*[]数组每个元素指向一个char型的变量,关键字数组记得zhongbie+1*/
 22     char shuangfuhao[2]={‘1‘,‘1‘};/*字符=1*/
 23     zhongbie=-1;
 24     for(i=0;i<15;i++)
 25     {    linshi[i]=NULL;}/*定义一个临时存放字符串的数组用作比较*/
 26     do
 27     {        
 28     m=0;/*初始化下标*/
 29     ch=zifu[p++];
 30     /*开始识别字符种别*/
 31     while(ch==‘ ‘)
 32     {
 33         ch=zifu[p++];   
 34     }
 35     /*识别关键字或者标识符*/
 36     if((ch>=‘a‘&&ch<=‘z‘)||(ch>=‘A‘&&ch<=‘Z‘))
 37     {
 38         while((ch>=‘0‘&&ch<=‘9‘)||(ch>=‘a‘&&ch<=‘z‘)||(ch>=‘A‘&&ch<=‘Z‘))/*将标识符存入临时数组*/
 39         {
 40             linshi[m++]=ch;
 41             ch=zifu[p++];
 42         }
 43         zhongbie=10;/*p=p+1下次识别就是p+1*/
 44         for(i=0;i<6;i++)  /*将识别出来的字符和已定义的关键字作比较 */
 45         {
 46             if(strcmp(linshi,guanjianzi[i])==0)
 47             {
 48                 zhongbie=i+1;
 49                 break;
 50             }
 51         }
 52         break;
 53     }
 54     /*识别数字*/
 55     else if((ch>=‘0‘&&ch<=‘9‘))
 56     {
 57         while((ch>=‘0‘&&ch<=‘9‘))
 58         {
 59             linshi[m++]=ch;
 60             ch=zifu[p++];
 61         }
 62         zhongbie=11;
 63         break;
 64     }
 65     else 
 66     {
 67         switch(ch)
 68         {
 69         case ‘:‘:
 70             linshi[m++]=ch;
 71             ch=zifu[p++];
 72             if(ch==‘=‘)
 73             {
 74                 zhongbie=18;
 75                 linshi[m++]=ch;
 76             }
 77             else
 78             {    zhongbie=17;}
 79             break;
 80         case ‘<‘:
 81             linshi[m++]=ch;
 82             ch=zifu[p++];
 83             if(ch==‘=‘)
 84             {
 85                 zhongbie=21;
 86                 linshi[m++]=ch;
 87             }
 88             else if(ch==‘>‘)
 89             {
 90                 zhongbie=22;
 91                 linshi[m++]=ch;
 92             }
 93             else
 94             {    zhongbie=20;}
 95             break;
 96         case ‘>‘:
 97                 linshi[m++]=ch;
 98             ch=zifu[p++];
 99             if(ch==‘=‘)
100             {
101                 zhongbie=24;
102                 linshi[m++]=ch;
103             }
104             else
105             {    zhongbie=23;}
106             break;
107         case ‘+‘:zhongbie=13;linshi[0]=ch;break;
108         case ‘-‘:zhongbie=14;linshi[0]=ch;break;
109         case ‘*‘:zhongbie=15;linshi[0]=ch;break;
110         case ‘/‘:zhongbie=16;linshi[0]=ch;break;
111         case ‘=‘:zhongbie=25;linshi[0]=ch;break;
112         case ‘;‘:zhongbie=26;linshi[0]=ch;break;
113         case ‘(‘:zhongbie=27;linshi[0]=ch;break;
114         case ‘)‘:zhongbie=28;linshi[0]=ch;break;
115         case ‘#‘:zhongbie=0;linshi[0]=ch;break;
116         }
117         break;
118     }
119     }while(zhongbie!=-1);
120 }