先序创建二叉树的问题

[Barcelooooooooona]

#include<iostream>
#include<malloc.h>
using namespace std;

typedef struct node
{
	char data;
	struct node *lchild;
	struct node *rchild;
}BTnode;

BTnode* CreateBiTree(BTnode *&T)
{
	char ch;
	cin >> ch;
	if (ch == ' ')
		return  NULL;
	else 
	{
		T = (BTnode*)malloc(sizeof(BTnode));
		T->data = ch;
		T->lchild=CreateBiTree(T->lchild);
		T->rchild=CreateBiTree(T->rchild);
		return T;
	}	
}

void PreOrder(BTnode *b)
{
	if (b != NULL)
	{
		cout << b->data;
		PreOrder(b->lchild);
		PreOrder(b->rchild);
	}
}
int main()
{
	BTnode *B = (BTnode*)malloc(sizeof(BTnode));
	B=CreateBiTree(B);
	PreOrder(B);
	return 0;
}

为什么没有输出的啊？求大神指导，谢谢了

[自信男孩]

#include<iostream>
#include<malloc.h>
using namespace std;

typedef struct node
{
    char data;
    struct node *lchild;
    struct node *rchild;
}BTnode;

BTnode* CreateBiTree(BTnode *&T)
{
    char ch;
    cin >>ch;
    if (ch == '#')    /*空格改成#*/
        return  NULL;
    else
    {
        T = (BTnode*)malloc(sizeof(BTnode));
        T->data = ch;
        T->lchild=CreateBiTree(T->lchild);
        T->rchild=CreateBiTree(T->rchild);
        return T;
    }
}

void PreOrder(BTnode *b)
{
    if (b != NULL)
    {
        cout << b->data;
        PreOrder(b->lchild);
        PreOrder(b->rchild);
    }
}
int main()
{
    BTnode *B = (BTnode*)malloc(sizeof(BTnode));
    B=CreateBiTree(B);
    PreOrder(B);
    return 0;
}

空格改成#,然后输入如下：

ABC##DE#G##F###

为什么不可以，主要是cin输入的问题，即cin不会将空格赋值给ch；

[Barcelooooooooona]

嗯，谢谢大神