二叉树的前中后遍历

#include<iostream>
#include<algorithm>
using namespace std;
typedef struct BTtree
{
	char ch;
	BTtree *l,*r;
};
void Create_tree(BTtree *&tree)
{   
	char c;
	cin>>c;
	if(c=='#')
	{
		tree=NULL;
		return ;
	}
	else
	{
		BTtree *p=new BTtree;
		p->ch=c;
		tree=p;
		Create_tree(tree->l);
		Create_tree(tree->r);
	}
}
void Pri_print(BTtree *tree)
{
	if(tree!=NULL)
	{
		printf("%c",tree->ch);
		Pri_print(tree->l);
		Pri_print(tree->r);
	}
	else return;
}
void In_print(BTtree *tree)
{
	if(tree!=NULL)
	{
		In_print(tree->l);
		printf("%c",tree->ch);
		In_print(tree->r);
	}
}
void Ed_print(BTtree *tree)
{
	if(tree!=NULL)
	{
		Ed_print(tree->l);
		Ed_print(tree->r);
		printf("%c",tree->ch);
	}
}
int main()
{
	printf("请输入二叉树：");
	BTtree *tree=new BTtree;
	Create_tree(tree);
	printf("前序遍历:");
	Pri_print(tree);
	printf("\n");
	printf("中序遍历:");
	In_print(tree);
	printf("\n");
	printf("后序遍历:");
	Ed_print(tree);
	printf("\n");
	return 0;
}