0916词法分析器

#include<stdio.h>
#include<string.h>
#define N 100
main()
{
    int j,i=0;
    char a[N],b[N];
    printf("请输入源程序：(以#结束)\n");
    gets(a);
    i=0;
    while(a[i]!=‘#‘)
    {
         if(a[i]>=65&&a[i]<=122)
        {
            j=0;
            while(a[i]!=‘ ‘&&a[i]!=‘#‘&&(a[i]>=65&&a[i]<=122))
            {
                b[j]=a[i];
                j++;
                i++;
            }
            i--;
            b[j]=‘\0‘;
            if(strcmp(b,"begin")==0) printf("<1,begin>\n");
            else if(strcmp(b,"if")==0) printf("<2,if>\n");
            else if(strcmp(b,"then")==0) printf("<3,then>\n");
            else if(strcmp(b,"while")==0) printf("<4,while>\n");
            else if(strcmp(b,"do")==0) printf("<5,do>\n");
            else if(strcmp(b,"end")==0) printf("<6,end>\n");
         }
         else
         {
            switch(a[i])
            {
            case ‘+‘: printf("<13,+>\n");break;
            case ‘-‘: printf("<14,->\n");break;
            case ‘*‘: printf("<15,*>\n");break;
            case ‘/‘: printf("<16,/>\n");break;
            case ‘:‘:if(a[i+1]==‘=‘)
                     {
                         printf("<18,:=>\n");
                         i++;
                     } 
                else printf("<17,:>\n");
                break;
            case ‘<‘: if(a[i+1]==‘=‘)
                     {
                         printf("<21,<=>\n");
                         i++;
                     }
                else if(a[i+1]==‘>‘)
                {
                    printf("<22,<>>\n");
                    i++;
                }
                else printf("<20,:>\n");
                break;
            case ‘>‘: if(a[i+1]==‘=‘)
                     {
                         printf("<24,>=>\n");
                         i++;
                     } 
                else printf("<23,>>\n");
                break;
            case ‘=‘: printf("<25,=>\n");break;
            case ‘;‘: printf("<26,;>\n");break;
            case ‘(‘: printf("<27,(>\n");break;
            case ‘)‘: printf("<28,)>\n");break;
            case‘ ‘: break;
            default:
                if(a[i]>=‘0‘&&a[i]<=‘9‘)    
                    printf("<11,%c>\n",a[i]);
                else 
                    printf("‘%c‘输入错误！\n",a[i]);
                    break;
            }
         }
         i++;
    }
}