0916 编程实验一 词法分析程序

#include<stdio.h>
#include<string.h>
#include <conio.h>
#include <ctype.h>
char prog[80],token[8],ch;

int p,syn,m,n,sum;
char *rwtab[6]={"begin","if","then","while","do","end"};

scaner()
{
sum=0;
for(m=0;m<8;m++)
token[m]='\0';
ch=prog[p++];
m=0;
while((ch==' ')||(ch=='\n'))
ch=prog[p++];
if(((ch<='z')&&(ch>='a'))||((ch<='Z')&&(ch>='A')))
{ while(((ch<='z')&&(ch>='a'))||((ch<='Z')&&(ch>='A'))||((ch>='0')&&(ch<='9')))
{token[m++]=ch;
ch=prog[p++];
}
p--;
syn=10;
for(n=0;n<6;n++)
if(strcmp(token,rwtab
)==0)
{ syn=n+1;
break;
}
}
else if((ch>='0')&&(ch<='9'))
{ while((ch>='0')&&(ch<='9'))
{ sum=sum*10+ch-'0';
ch=prog[p++];
}
p--;
syn=11;
}
else
switch(ch)
{
case '<':token[m++]=ch;
ch=prog[p++];
if(ch=='=') {
syn=21;
token[m++]=ch; }
else if(ch=='>'){
syn=22;
token[m++]=ch; }
else  {
syn=20;
p--;  }
break;
case '>':token[m++]=ch;
ch=prog[p++];
if(ch=='=') {
syn=24;
token[m++]=ch; }
else  {
syn=23;
p--; }
break;
case '+':syn=13;
token[m++]=ch;
break;
case '-':syn=14;
token[m++]=ch;
break;
case '*': syn=15;
token[m++]=ch;
break;
case '/': syn=16;
token[m++]=ch;
break;
case ':': token[m++]=ch;
ch=prog[p++];
if(ch=='=') {
syn=18;
token[m++]=ch; }
else  {
syn=17;
p--; }
break;
case '=':syn=25;
token[m++]=ch;
break;
case '(': syn=27;
token[m++]=ch;
break;
case ')': syn=28;
token[m++]=ch;
break;
case ';': syn=26;
token[m++]=ch;
break;
case '#': syn=0;
token[m++]=ch;
break;
default: syn=-1;
break;
}
token[m++]='\0';
}

main()
{
p=0;
printf("\nplease input a string(end with #):\n");
do{
scanf("%c",&ch);
prog[p++]=ch;

}while(ch!='#');

p=0;

do{
scaner();
switch(syn)
{case 11:printf("( %-10d%5d )\n",sum,syn);
break;
case -1:printf("you have input a wrong string\n");
getch();
break;
default: printf("( %-10s%5d )\n",token,syn);
break;
}
}while(syn!=0);
getch();
}