1 #include
     
        2 #include
      
         3 #include
       
          4 char prog[800],token[8];  5 char ch;  6 int syn,p,q,sum;  7 char *rwtab[6]={
   "begin","if","then","while","do","end"};  8 void scaner();  9 main() 10 { 11     p=0; 12     printf("\nplease input the source code:\n"); 13     do{ 14         ch=getchar(); 15         prog[p]=ch; 16         p++; 17     }while(ch!='#'); 18     p=0; 19     do 20     { 21         scaner(); 22         switch(syn) 23         { 24             case 11:printf("\n(%d,%d)",syn,sum);break; 25             case -1:printf("\n(%s,出错)",token);break; 26             default:printf("\n(%d,%s)",syn,token); 27         } 28     }while(syn!=0); 29 } 30  31  32 void scaner() 33 { 34  35     int i; 36     sum=0; 37     for(q=0;q<8;q++) 38         token[q]=NULL; 39     ch=prog[p]; 40     q=0; 41     while(ch==' '||ch=='\n') 42     { 43         p++; 44         ch=prog[p];     45     } 46     if(('a'<=ch)&&(ch<='z')||('A'<=ch)&&(ch<='Z')) 47     { 48         while(('a'<=ch)&&(ch<='z')||('A'<=ch)&&(ch<='Z')||(ch>='0'&&ch<='9')) 49         { 50             token[q]=ch; 51             p++; 52             ch=prog[p];     53              54             q++; 55         } 56         syn=10; 57         for(i=0;i<6;i++) 58         { 59              if(strcmp(token,rwtab[i])==0) 60              { 61                  syn=i+1; 62                  break; 63              }     64         } 65     } 66     else if(ch>='0'&&ch<='9') 67     { 68         while((ch>='0')&&(ch<='9')) 69         { 70             sum=sum*10+ch-'0'; 71             p++; 72             ch=prog[p]; 73         } 74         syn=11; 75     } 76     else switch(ch) 77     { 78         case '+': 79              syn=13; 80              token[q++]=ch; 81              p++; 82              break; 83         case '-': 84             syn=14; 85              token[q++]=ch; 86              p++; 87              break; 88         case '*': 89             syn=15; 90              token[q++]=ch; 91              p++; 92              break; 93         case '/': 94             syn=16; 95              token[q++]=ch; 96              p++; 97              break; 98         case ':': 99             syn=17;100              token[q++]=ch;101              p++;102              if(prog[p]=='=')103              {104                  syn=18;105                  ch=prog[p];106                  token[q++]=ch;107                  p++;108              }109              break;110         case '<':111             syn=20;112              token[q++]=ch;113              p++;114              if(prog[p]=='>')115              {116                  syn=21;117                  ch=prog[p];118                  token[q++]=ch;119                  p++;120              }121              if(prog[p]=='=')122              {123                  syn=22;124                  ch=prog[p];125                  token[q++]=ch;126                  p++;127              }128              break;129         case '>':130             syn=23;131              token[q++]=ch;132              p++;133               if(prog[p]=='=')134              {135                  syn=24;136                  ch=prog[p];137                  token[q++]=ch;138                  p++;139              }140              break;141         case '=':142             syn=25;143              token[q++]=ch;144              p++;145              break;146         case ';':147             syn=26;148              token[q++]=ch;149              p++;150              break;151         case '(':152             syn=27;153              token[q++]=ch;154              p++;155              break;156         case ')':157             syn=28;158              token[q++]=ch;159              p++;160              break;161           case '#':162              syn=0;163              token[q++]=ch;164              break;165     }166 }