编译程序初级,词法分析

#include<stdio.h>
#include<string.h>
char prog[80],token[8];
char ch;
int syn,p,m,n,sum;
char *rwtab[6]={"begin","if","then","while","do","end"};
scaner();
void main()
{
 p=0;
 printf("/n please input string :/n");
 do
 {
    scanf("%c",&ch);
       prog[p++]=ch;      
 }
 while(ch!='#');
 p=0;
 do
 {
        scaner();
  switch(syn)
  {
  case 11:
   printf("(%d,%d)/n",syn,sum);
   sum=0;
   break;
  case -1:
   printf("wrong!!/n");
   break;
  default:
   printf("(%d,%s)/n",syn,rwtab[syn-1]);
            break;
  }
 }
 while(syn!=0);
}

scaner()
{  
 m=0;
 for(n=0;n<8;n++)
  token[n]=NULL;
 
 ch=prog[p++];
 while(ch==' ')
  ch=prog[p++];
 if((ch>='a')&&(ch<='z')||(ch>='A')&&(ch<='Z'))
 {
  while((ch>='a')&&(ch<='z')||(ch>='A')&&(ch<='Z')||(ch>='0')&&(ch<='9'))
  {
   
   token[m++]=ch;
   ch=prog[p++];
  }
  token[m++]='/0';
  p--;
  syn=10;
  for(n=0;n<6;n++)
   if(strcmp(token,rwtab[n])==0)
   {
    syn=n+1;
    break;
   }
 }
 else
  if(ch>='0'&&ch<='9')
  {
   while(ch>='0'&&ch<='9')
   {
    sum=sum*10+ch-'0';
    ch=prog[p++];
   }
   ch=prog[p--];
   syn=11;
  }
  else
   switch(ch)
  {
   case'<':
    m=0;
    token[m++]=ch;
    ch=prog[p++];
    if(ch=='>')
    {
     syn=21;
     token[m++]=ch;
    }
    else if(ch=='=')
    {
     syn=22;
     token[m++]=ch;
    }
    else
    {
     syn=20;
     ch=prog[p--];
    }
    break;
   case'>':
                m=0;
    token[m++]=ch;
    ch=prog[p++];
    if(ch=='=')
    {
     syn=24;
     token[m++]=ch;
    }
    else
    {
     syn=23;
     ch=prog[p--];
    }
    break;
   case':':
                m=0;
    token[m++]=ch;
                ch=prog[p++];
    if(ch=='=')
    {
     syn=18;
                    token[m++]=ch;
    }
    else
    {
     syn=17;
     ch=prog[p--];
    }
    break;
   case'+':
    syn=13;
    token[0]=ch;
    break;
   case'-':
    syn=14;
    token[0]=ch;
                break;
   case'*':
    syn=15;
    token[0]=ch;
                break;
   case'/':
    syn=16;
    token[0]=ch;
                break;
   case';':
    syn=26;
    token[0]=ch;
                break;
   case'(':
    syn=27;
    token[0]=ch;
                break;
   case')':
    syn=29;
    token[0]=ch;
                break;
   case'#':
    syn=0;
    token[0]=ch;
                break;
   default:
    syn=-1;
  }
}