编写程序实现二叉树的创建，三种遍历自己销毁

#include <myhead.h>
//树结点
typedef struct Node
{
	char data;
	struct Node* lchild;
	struct Node* rchild;
}*Btree;
//结点创建
Btree create_node()
{
    Btree t=(Btree)malloc(sizeof(struct Node));
    if(NULL ==t)
        return NULL;
    t->data=0; 
    t->lchild=t->rchild=NULL;
    return t;
}
//二叉树创建
Btree create_tree()
{
	char element;
	printf("请输入字符:");
	scanf("%c",&element);
	getchar();
	if(element == '#')
		return NULL;
	Btree tree = create_node();
	tree->data = element;
	tree->lchild = create_tree();
	tree->rchild = create_tree();
	return tree;
}
//先序
void first_output(Btree tree)
{
	if(NULL == tree)
		return;
	printf("%c",tree->data);
	first_output(tree->lchild);
	first_output(tree->rchild);
}
//中序
void mid_output(Btree tree)
{
	if(NULL == tree)
		return;
	mid_output(tree->lchild);
	printf("%c",tree->data);
	mid_output(tree->rchild);
}
//后序
void last_output(Btree tree)
{
	if(NULL == tree)
		return;
	last_output(tree->lchild);
	last_output(tree->rchild);
	printf("%c",tree->data);
}
//释放
Btree free_space(Btree tree)
{
    if(NULL ==tree)
        return NULL;
    free_space(tree->lchild);
    free_space(tree->rchild);
    free(tree);
	tree=NULL;
}
int main(int argc, const char *argv[])
{
	Btree tree = NULL;
	tree = create_tree();
	printf("先序遍历:");
	first_output(tree);
	printf("\n中序遍历:");
	mid_output(tree);
	printf("\n后序遍历:");
	last_output(tree);
	printf("\n");
	//释放
	free_space(tree);
	return 0;
}