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);
}