C/C++上机题，求救呀

Question

Answer 1

 Linux环境下编译的，试过没有问题。

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

//ABC^^DE^G^^F^^^

struct bi_node{
	char data;
	struct bi_node *lchild;
	struct bi_node *rchild;
};

int create_bi_node(struct bi_node **node)
{
	char ch;
	int ret = 0;
	struct bi_node *temp_node;

	*node = NULL;
	scanf("%c", &ch);
	//判断节点是否空
	if(ch == '^'){
		return 0;
	}
	//分配节点内存
	temp_node = malloc(sizeof(struct bi_node));
	if(!temp_node)
		return -1;
		
	temp_node->data = ch;

	ret = create_bi_node(&temp_node->lchild);//左节点
	ret |= create_bi_node(&temp_node->rchild);//右节点
	
	*node = temp_node;
	return ret;
}

void print_pre_order(struct bi_node *node){
	
	if(!node)
		return;
	printf("%c", node->data);
	print_pre_order(node->lchild);
	print_pre_order(node->rchild);
}

void print_in_order(struct bi_node *node){
	
	if(!node)
		return;

	print_in_order(node->lchild);
	printf("%c", node->data);
	print_in_order(node->rchild);
}

void print_post_order(struct bi_node *node){
	
	if(!node)
		return;

	print_post_order(node->lchild);
	print_post_order(node->rchild);
	printf("%c", node->data);
}

int main(int argc, char *argv[])
{
	struct bi_node *bi_tree_node = NULL;
	
	if(create_bi_node(&bi_tree_node) ==0)
	{
		printf("\nPre Order:");
		print_pre_order(bi_tree_node);
		printf("\nIn Order:");
		print_in_order(bi_tree_node);
		printf("\nPost Order:");
		print_post_order(bi_tree_node);
		printf("\n");
		printf("Create biTree Sucess!\n\n");
	}else{
		printf("Create biTree error!\n");
	}
}