C语言 如何实现迭代创建二叉树的函数?

Question

我尝试通过使用迭代函数来创建二叉树来实现它。我很困惑为什么我得到一个无限循环作为我的输出。我相信正在使用的函数没有问题。但如果有人能告诉我到底是什么导致了这个错误，我将不胜感激。

#include<stdio.h>
#include<stdlib.h>
typedef struct node{
int data;
struct node *left,*right;
} NODE;
NODE* createNode(int ele){
NODE* newnode = (NODE*)malloc(sizeof(NODE));
newnode->data = ele;
newnode->left = NULL;
newnode->right = NULL;
return newnode;
}
void inorder(NODE* root){
while(root != NULL){
inorder(root->left);
printf(" %d ",root->data);
inorder(root->right);
}
}

void preorder(NODE* root){
while(root != NULL){
printf(" %d ",root->data);
preorder(root->left);
preorder(root->right);
}
}
void postorder(NODE* root){
while(root != NULL){
postorder(root->left);
postorder(root->right);
printf(" %d ",root->data);
}
}

void createTree(NODE** root, int ele){
NODE* newnode = createNode(ele);
if(*root == NULL){
//set newnode as root
*root = newnode;
return;
}
NODE* curr = *root;
while (1){
// If the data of the new node is less than the data of the current node,
// go to the left child
if(ele <  curr->data){
// If the left child is empty, insert the new node here
if(curr->left == NULL){
curr->left = newnode;
return;
}
curr = curr->left;
}
// If the data of the new node is greater than or equal to the data of the current node,
// go to the right child
else{
if (curr->right == NULL){
curr->right = newnode;
return; 
}
curr = curr->right;
}
}
}
int main(){
NODE* root = NULL;
int data;
while(1){
printf("Enter the data for the root node of the binary tree(Enter -1 to stop): n");
scanf("%d",&data);
createTree(&root,data);
if(data == -1){
break;
}
}
printf("nPreorder traversal:n");
preorder(root);
printf("nInorder traversal:n");
inorder(root);

printf("nPostorder traversal:n");
postorder(root);

return 0;
}

Answer 1

打印函数中，

while(root != NULL){

将导致无限循环，因为root永远不会改变。

你可能想要

if(root != NULL){