C语言二叉树中序遍历？

以下是C语言实现二叉树中序遍历的迭代算法的示例代码：

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

// 定义二叉树结点的结构体
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
};

// 定义栈的结构体
struct Stack {
    struct TreeNode **data;
    int top;
    int maxSize;
};

// 初始化栈
void initStack(struct Stack *s, int maxSize) {
    s->data = (struct TreeNode **)malloc(sizeof(struct TreeNode *) * maxSize);
    s->top = -1;
    s->maxSize = maxSize;
}

// 判断栈是否为空
int isEmpty(struct Stack *s) {
    return s->top == -1;
}

// 判断栈是否已满
int isFull(struct Stack *s) {
    return s->top == s->maxSize - 1;
}

// 入栈
void push(struct Stack *s, struct TreeNode *node) {
    if (isFull(s)) {
        return;
    }
    s->data[++(s->top)] = node;
}

// 出栈
struct TreeNode *pop(struct Stack *s) {
    if (isEmpty(s)) {
        return NULL;
    }
    return s->data[(s->top)--];
}

// 中序遍历二叉树
void inorderTraversal(struct TreeNode *root) {
    if (root == NULL) {
        return;
    }
    
    struct Stack stack;
    initStack(&stack, 100); // 假设最大结点数为100
    
    struct TreeNode *current = root;
    while (current != NULL || !isEmpty(&stack)) {
        while (current != NULL) {
            push(&stack, current);
            current = current->left;
        }
        
        current = pop(&stack);
        printf("%d ", current->val);
        
        current = current->right;
    }
}

int main() {
    // 构造二叉树
    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->left->left = NULL;
    root->left->right = NULL;
    root->right = (struct TreeNode *)malloc(sizeof(struct TreeNode));
    root->right->val = 3;
    root->right->left = NULL;
    root->right->right = NULL;
    
    // 中序遍历二叉树
    inorderTraversal(root); // 输出：2 1 3
    
    return 0;
}