c语言按层次遍历二叉树代码

这个问题可以回答。以下是C语言按层次遍历二叉树的代码：

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

#define MAX_QUEUE_SIZE 100 // 定义队列的最大长度

// 定义二叉树的节点结构体
typedef struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
} TreeNode;

// 定义队列结构体
typedef struct Queue {
    int front, rear;
    TreeNode* arr[MAX_QUEUE_SIZE];
} Queue;

// 初始化队列
Queue* createQueue() {
    Queue* q = (Queue*)malloc(sizeof(Queue));
    q->front = -1;
    q->rear = -1;
    return q;
}

// 判断队列是否为空
int isQueueEmpty(Queue* q) {
    return (q->front == -1 && q->rear == -1);
}

// 入队
void enqueue(Queue* q, TreeNode* node) {
    if (q->rear == MAX_QUEUE_SIZE - 1) {
        printf("Queue overflow");
        return;
    }
    // 如果队列为空，需要更新front
    if (q->front == -1) {
        q->front = 0;
    }
    q->rear++;
    q->arr[q->rear] = node;
}

// 出队
TreeNode* dequeue(Queue* q) {
    if (isQueueEmpty(q)) {
        printf("Queue underflow");
        exit(1);
    }
    TreeNode* node = q->arr[q->front];
    if (q->front == q->rear) {
        q->front = -1;
        q->rear = -1;
    } else {
        q->front++;
    }
    return node;
}

// 层次遍历二叉树
void levelOrderTraversal(TreeNode* root) {
    if (root == NULL) {
        return;
    }
    Queue* q = createQueue();
    enqueue(q, root);
    while (!isQueueEmpty(q)) {
        TreeNode* node = dequeue(q);
        printf("%d ", node->val);
        if (node->left != NULL) {
            enqueue(q, node->left);
        }
        if (node->right != NULL) {
            enqueue(q, node->right);
        }
    }
}

// 创建二叉树
TreeNode* createTree() {
    TreeNode* root = (TreeNode*)malloc(sizeof(TreeNode));
    root->val = 1;
    root->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->val = 2;
    root->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->val = 3;
    root->left->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->left->val = 4;
    root->left->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->right->val = 5;
    root->right->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->left->val = 6;
    root->right->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->right->val = 7;
    return root;
}

int main() {
    TreeNode* root = createTree();
    levelOrderTraversal(root);
    return 0;
}