不用递归，用栈实现二叉树的中序遍历、先序遍历、后续遍历C语言代码

好的，以下是C语言代码实现二叉树的中序遍历、先序遍历、后续遍历，使用栈而非递归：

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

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

void inorderTraversal(struct TreeNode* root) {
    struct TreeNode* stack[100];
    int size = 0;
    while (root || size) {
        while (root) {
            stack[size++] = root;
            root = root->left;
        }
        root = stack[--size];
        printf("%d ", root->data);
        root = root->right;
    }
}

void preorderTraversal(struct TreeNode* root) {
    struct TreeNode* stack[100];
    int size = 0;
    while (root || size) {
        while (root) {
            printf("%d ", root->data);
            stack[size++] = root;
            root = root->left;
        }
        root = stack[--size];
        root = root->right;
    }
}

void postorderTraversal(struct TreeNode* root) {
    struct TreeNode* stack[100];
    int size = 0;
    struct TreeNode* lastVisited = root;
    while (root || size) {
        while (root) {
            stack[size++] = root;
            root = root->left;
        }
        root = stack[size - 1];
        if (root->right && root->right != lastVisited) {
            root = root->right;
        } else {
            printf("%d ", root->data);
            lastVisited = root;
            size--;
            root = NULL;
        }
    }
}

int main() {
    struct TreeNode a = {4, NULL, NULL};
    struct TreeNode b = {5, NULL, NULL};
    struct TreeNode c = {2, &a, &b};
    struct TreeNode d = {6, NULL, NULL};
    struct TreeNode e = {3, &d, NULL};
    struct TreeNode f = {1, &c, &e};
    inorderTraversal(&f);
    printf("\n");
    preorderTraversal(&f);
    printf("\n");
    postorderTraversal(&f);
    printf("\n");
    return 0;
}

请注意，这只是实现的一种方法，并不是唯一的正确答案。