词法分析2

#include <stdio.h>  
#include <string.h>
#define max 100  
char a[max],b[8],ch;  
int syn,p,m,n,sum;  
char word[][6]={"begin","if","then","while","do","end"};   
void mor()
{    
    sum=0;  
    ch=a[p++];  
    m=0;      
    while((ch==' ')||(ch=='\n')||(ch=='\t'))  
        ch=a[p++];  
    if(((ch<='z')&&(ch>='a'))||((ch<='Z')&&(ch>='A')))  
    {
        while(((ch<='z')&&(ch>='a'))||((ch<='Z')&&(ch>='A'))||((ch>='0')&&(ch<='9')))  
        {  
            b[m++]=ch;  
            ch=a[p++];  
        }    
        p--; 
        syn=10;                    
        for(n=0;n<6;n++)  
           if(strcmp(b,word[n])==0)   
           {
               syn=n+1;  
               break;  
           }  
    }                                   
    else if((ch>='0')&&(ch<='9'))  
    {   
       while((ch>='0')&&(ch<='9'))  
       {  
           sum=sum*10+ch-'0';    
           ch=a[p++];  
       }  
       p--;  
       syn=11;  
    }  
    else                  
    {  
        switch(ch)  
        {  
        case '+':  
            syn=13;  
            b[m++]=ch;          
            break;  
        case '-':   
            syn=14;
            b[m++]=ch;   
            break; 
        case '*':  
            syn=15;  
            b[m++]=ch;  
            break;  
        case '/':  
            syn=16;  
            b[m++]=ch;  
            break;  
        case ':':  
            b[m++]=ch;  
            ch=a[p++];  
            if(ch=='=')  
            {  
                syn=18;  
                b[m++]=ch;  
            }  
            else  
            {   
                syn=18;  
                p--;  
            }  
            break; 
        case '<':
            b[m++]=ch;  
            ch=a[p++];  
            if(ch=='=')  
            {   
                syn=21;  
                b[m++]=ch;  
            }  
            else  
            {    
                syn=20;  
                p--;  
            }  
            break;  
        case '>':  
            b[m++]=ch;  
            ch=a[p++];  
            if(ch=='=')  
            {  
                syn=24;  
                b[m++]=ch;  
            }  
            else  
            {   
                syn=23;  
                p--;  
            }  
            break;
        case '=':  
            syn=25;  
            b[m++]=ch;  
            break;  
        case ';':  
            syn=26;  
            b[m++]=ch;  
            break;  
        case '(':   
            syn=27;  
            b[m++]=ch;  
            break;  
        case ')':  
            syn=28;  
            b[m++]=ch;  
            break;  
        case '#':   
            syn=0;  
            b[m++]=ch;  
            break; 
        case '!': 
            syn=-2;
            break;
        default:  
            syn=-1;  
            break;  
        }  
    }  
    b[m++]='\0';  
}
main()  
{
    p=0;  
    printf("请输入一段程序段，便于词法分析(以!作为结束符):"); 
    do{
        scanf("%c",&a[p++]);    
    }while(a[p-1]!='!');     
    p=0;  
    do{  
        mor();  
        switch(syn)  
        {  
            case 11:  
                printf("( %-5d%10d )\n",syn,sum);  
                break;  
            case -1:  
                printf("你输入一个错的字符\n");    
                return 0;  
                break;
            case -2:
                break;
            default:   
                printf("( %-5d%10s )\n",syn,b);  
                break;  
        }  
    }while(syn!=-2);  
}