递归下降的语法分析编程实现

#include <stdio.h>
#include<dos.h>
#include<stdlib.h>
#include<string.h>

char a[50] ,b[50],d[200],e[10];
char ch;
int n1,i1=0,flag=1,n=5;

int S();
int B();
int C();
void input();
void input1();
void output();


void main()                      /*递归分析*/
{
    int f,p,j=0;
    char x;
    d[0]='S';
    d[1]='=';
    d[2]='>';
    d[3]='a';
    d[4]='S';
    d[5]='e';
    d[6]='#';
    printf("请输入字符串(长度<50,以#号结束）\n");
    do

    {
        scanf("%c",&ch);
        a[j]=ch;
        j++;
    }while(ch!='#');
    n1=j;
    ch=b[0]=a[0];
    printf("文法\t分析串\t\t分析字符\t剩余串\n");
    f=S();
    if (f==0) return;
    if (ch=='#')  
    {   printf("accept\n");
        p=0;
        x=d[p];
        while(x!='#')
        {
            printf("%c",x);p=p+1;x=d[p];          /*输出推导式*/
        }
    }
    else {
        printf("error\n");
        printf("回车返回\n");
        getchar();getchar(); 
        return; 
    }
    printf("\n");
    printf("回车返回\n");
    getchar();
    getchar();
}