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