#include "stdafx.h"
#include "stdio.h"
#include "string.h"
#include "stdlib.h"
#define NULL 0
typedef struct bitnode
{   
    char data;   
    struct bitnode *lchild,*rchild;
}bitnode,*bitree;
bitree create(bitree t)//为什么一直输入字符？而不不能退出，程序该如何修改？
{   
    char ch;   
    scanf("%c",&ch);   
    if(ch=='#')
    {
        t=NULL;
    }
    else
    {        
            t=(bitree)malloc(sizeof(bitnode));        
            t->data=ch;   
         
            t->lchild=create(t->lchild);        
            t->rchild=create(t->rchild);  
        }   
   
    return t;
}

void preorder(bitree t)
{   
    if(t)
    {        
        printf("%c",t->data);         
        preorder(t->lchild);               
        preorder(t->rchild);      
      
    }
}

int main(int argc, char* argv[])
{
    bitree t=NULL;   
    t=create(t);   
    preorder(t);
    return 0;
}