c语言实现二叉树的前中后序遍历非递归完整代码

以下是C语言实现二叉树的前中后序遍历非递归完整代码：

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

#define MAXSIZE 100

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

typedef struct Stack {
    TreeNode *data[MAXSIZE];
    int top;
} Stack;

void initStack(Stack *s) {
    s->top = -1;
}

int isEmpty(Stack *s) {
    return s->top == -1;
}

int isFull(Stack *s) {
    return s->top == MAXSIZE - 1;
}

void push(Stack *s, TreeNode *node) {
    if (isFull(s)) {
        printf("Stack is full.\n");
        return;
    }
    s->data[++s->top] = node;
}

TreeNode *pop(Stack *s) {
    if (isEmpty(s)) {
        printf("Stack is empty.\n");
        return NULL;
    }
    return s->data[s->top--];
}

TreeNode *createTree() {
    int val;
    scanf("%d", &val);
    if (val == -1) {
        return NULL;
    }
    TreeNode *root = (TreeNode *)malloc(sizeof(TreeNode));
    root->val = val;
    root->left = createTree();
    root->right = createTree();
    return root;
}

void preOrder(TreeNode *root) {
    if (root == NULL) {
        return;
    }
    Stack s;
    initStack(&s);
    push(&s, root);
    while (!isEmpty(&s)) {
        TreeNode *node = pop(&s);
        printf("%d ", node->val);
        if (node->right != NULL) {
            push(&s, node->right);
        }
        if (node->left != NULL) {
            push(&s, node->left);
        }
    }
}

void inOrder(TreeNode *root) {
    if (root == NULL) {
        return;
    }
    Stack s;
    initStack(&s);
    TreeNode *node = root;
    while (node != NULL || !isEmpty(&s)) {
        while (node != NULL) {
            push(&s, node);
            node = node->left;
        }
        node = pop(&s);
        printf("%d ", node->val);
        node = node->right;
    }
}

void postOrder(TreeNode *root) {
    if (root == NULL) {
        return;
    }
    Stack s1, s2;
    initStack(&s1);
    initStack(&s2);
    push(&s1, root);
    while (!isEmpty(&s1)) {
        TreeNode *node = pop(&s1);
        push(&s2, node);
        if (node->left != NULL) {
            push(&s1, node->left);
        }
        if (node->right != NULL) {
            push(&s1, node->right);
        }
    }
    while (!isEmpty(&s2)) {
        TreeNode *node = pop(&s2);
        printf("%d ", node->val);
    }
}

int main() {
    TreeNode *root = createTree();
    printf("Preorder traversal: ");
    preOrder(root);
    printf("\nInorder traversal: ");
    inOrder(root);
    printf("\nPostorder traversal: ");
    postOrder(root);
    return 0;
}