给我按层次顺序遍历二叉树的c++算法的代码

以下是基于递归的二叉树按层次顺序遍历的C代码：

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

// 定义树的节点
struct Node {
    int data;
    struct Node* left;
    struct Node* right;
};

// 定义队列结构体及方法
struct Queue {
    struct Node** items;
    int front, rear, size;
};

struct Queue* createQueue(int capacity) {
    struct Queue* queue = (struct Queue*)malloc(sizeof(struct Queue));
    queue->items = (struct Node**)malloc(capacity * sizeof(struct Node*));
    queue->size = capacity;
    queue->front = 0;
    queue->rear = -1;

    return queue;
}

int isEmpty(struct Queue* queue) {
    return queue->rear == -1;
}

void enqueue(struct Queue* queue, struct Node* item) {
    if (queue->rear == queue->size - 1) {
        printf("Queue is full!\n");
        return;
    }

    queue->rear++;
    queue->items[queue->rear] = item;
}

struct Node* dequeue(struct Queue* queue) {
    if (isEmpty(queue)) {
        printf("Queue is empty!\n");
        return NULL;
    }

    struct Node* item = queue->items[queue->front];
    queue->front++;

    if (queue->front > queue->rear) {
        queue->front = 0;
        queue->rear = -1;
    }

    return item;
}

// 定义遍历方法
void levelOrder(struct Node* root) {
    struct Queue* queue = createQueue(100);

    if (root == NULL) return;

    enqueue(queue, root);

    while (!isEmpty(queue)) {
        struct Node* node = dequeue(queue);
        printf("%d ", node->data);

        if (node->left != NULL)
            enqueue(queue, node->left);

        if (node->right != NULL)
            enqueue(queue, node->right);
    }
}

// 创建节点
struct Node* createNode(int data) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));

    if (newNode == NULL) {
        printf("Memory allocation failed!\n");
        return NULL;
    }

    newNode->data = data;
    newNode->left = NULL;
    newNode->right = NULL;

    return newNode;
}

// 初始化二叉树
struct Node* initTree() {
    struct Node* root = createNode(1);
    root->left = createNode(2);
    root->right = createNode(3);
    root->left->left = createNode(4);
    root->left->right = createNode(5);
    root->right->left = createNode(6);
    root->right->right = createNode(7);

    return root;
}

// 主函数
int main() {
    struct Node* root = initTree();

    printf("按层次顺序遍历二叉树: ");
    levelOrder(root);
    printf("\n");

    return 0;
}