非递归方式遍历二叉树用C语言写个代码

好的，下面是用C语言实现非递归方式遍历二叉树的代码，以中序遍历为例：

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

// 二叉树结构体
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
};

// 栈结构体
struct Stack {
    struct TreeNode **data; // 存储二叉树节点指针的数组
    int top; // 栈顶指针
    int size; // 栈的大小
};

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

// 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->size - 1;
}

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

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

// 中序遍历
void inorderTraversal(struct TreeNode *root) {
    if (!root) {
        return;
    }

    struct Stack *s = initStack(100); // 初始化栈
    struct TreeNode *p = root;

    while (p || !isEmpty(s)) {
        if (p) {
            push(s, p); // 将当前节点入栈
            p = p->left; // 继续遍历左子树
        } else {
            p = pop(s); // 弹出栈顶节点
            printf("%d ", p->val); // 访问当前节点
            p = p->right; // 继续遍历右子树
        }
    }

    free(s->data); // 释放栈的内存空间
    free(s);
}

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 = (struct TreeNode *)malloc(sizeof(struct TreeNode));
    root->right->left->val = 4;
    root->right->left->left = NULL;
    root->right->left->right = NULL;
    root->right->right = (struct TreeNode *)malloc(sizeof(struct TreeNode));
    root->right->right->val = 5;
    root->right->right->left = NULL;
    root->right->right->right = NULL;

    inorderTraversal(root); // 中序遍历

    // 释放二叉树的内存空间
    free(root->left);
    free(root->right->left);
    free(root->right->right);
    free(root);
    
    return 0;
}

运行结果为：2 1 4 3 5。