用C语言写一个函数，层序遍历二叉树

好的，下面是用C语言实现二叉树层序遍历的代码：

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

struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
};

struct QueueNode {
    struct TreeNode *data;
    struct QueueNode *next;
};

struct Queue {
    struct QueueNode *front;
    struct QueueNode *rear;
};

void initQueue(struct Queue *q) {
    q->front = NULL;
    q->rear = NULL;
}

int isEmpty(struct Queue *q) {
    return q->front == NULL;
}

void enqueue(struct Queue *q, struct TreeNode *node) {
    struct QueueNode *newNode = (struct QueueNode *)malloc(sizeof(struct QueueNode));
    newNode->data = node;
    newNode->next = NULL;
    if (isEmpty(q)) {
        q->front = newNode;
        q->rear = newNode;
    } else {
        q->rear->next = newNode;
        q->rear = newNode;
    }
}

struct TreeNode *dequeue(struct Queue *q) {
    if (isEmpty(q)) {
        return NULL;
    }
    struct QueueNode *temp = q->front;
    struct TreeNode *result = temp->data;
    q->front = q->front->next;
    if (q->front == NULL) {
        q->rear = NULL;
    }
    free(temp);
    return result;
}

void levelOrder(struct TreeNode *root) {
    if (root == NULL) return;
    struct Queue q;
    initQueue(&q);
    enqueue(&q, root);
    while (!isEmpty(&q)) {
        struct TreeNode *node = dequeue(&q);
        printf("%d ", node->val);
        if (node->left) enqueue(&q, node->left);
        if (node->right) enqueue(&q, node->right);
    }
}

int main() {
    // 创建二叉树
    struct TreeNode *root = (struct TreeNode *)malloc(sizeof(struct TreeNode));
    root->val = 1;
    root->left = (struct TreeNode *)malloc(sizeof(struct TreeNode));
    root->left->val = 2;
    root->right = (struct TreeNode *)malloc(sizeof(struct TreeNode));
    root->right->val = 3;
    root->left->left = (struct TreeNode *)malloc(sizeof(struct TreeNode));
    root->left->left->val = 4;
    root->left->right = (struct TreeNode *)malloc(sizeof(struct TreeNode));
    root->left->right->val = 5;
    root->right->left = (struct TreeNode *)malloc(sizeof(struct TreeNode));
    root->right->left->val = 6;
    root->right->right = (struct TreeNode *)malloc(sizeof(struct TreeNode));
    root->right->right->val = 7;
    root->left->left->left = NULL;
    root->left->left->right = NULL;
    root->left->right->left = NULL;
    root->left->right->right = NULL;
    root->right->left->left = NULL;
    root->right->left->right = NULL;
    root->right->right->left = NULL;
    root->right->right->right = NULL;
    // 层序遍历
    printf("层序遍历结果：");
    levelOrder(root);
    printf("\n");
    return 0;
}

这里使用一个队列来辅助进行层序遍历，首先将根节点入队，然后依次出队并打印节点值，再将该节点的左右子节点入队，直到队列为空。