二叉树非递归遍历c语言

二叉树的非递归遍历可以使用栈来实现。以下是C语言的实现思路：

1. 将树的所有节点标志位置为假（0），并将根节点压入栈中进入循环。
2. 只要栈中元素个数大于0，进行循环操作弹出栈顶元素。
3. 如果栈顶元素标志为真，直接输出，进行下次循环即可。
4. 如果栈顶元素标志为假，将标志改为真，并将栈顶节点的右子树、根、左子树压入栈中，再执行下次循环。

以下是C语言的代码实现：

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

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

typedef struct Stack {
    TreeNode **data;
    int top;
    int size;
} Stack;

Stack *createStack(int size) {
    Stack *stack = (Stack *)malloc(sizeof(Stack));
    stack->data = (TreeNode **)malloc(sizeof(TreeNode *) * size);
    stack->top = -1;
    stack->size = size;
    return stack;
}

void push(Stack *stack, TreeNode *node) {
    if (stack->top == stack->size - 1) {
        return;
    }
    stack->top++;
    stack->data[stack->top] = node;
}

TreeNode *pop(Stack *stack) {
    if (stack->top == -1) {
        return NULL;
    }
    TreeNode *node = stack->data[stack->top];
    stack->top--;
    return node;
}

void inorderTraversal(TreeNode *root) {
    if (root == NULL) {
        return;
    }
    Stack *stack = createStack(100);
    TreeNode *node = root;
    while (node != NULL || stack->top != -1) {
        while (node != NULL) {
            push(stack, node);            node = node->left;
        }
        node = pop(stack);
        printf("%d ", node->val);
        node = node->right;
    }
}

int main() {
    TreeNode *root = (TreeNode *)malloc(sizeof(TreeNode));
    root->val = 1;    root->left = (TreeNode *)malloc(sizeof(TreeNode));
    root->left->val = 2;
    root->left->left = NULL;
    root->left->right = NULL;
    root->right = (TreeNode *)malloc(sizeof(TreeNode));
    root->right->val = 3;
    root->right->left = NULL;
    root->right->right = NULL;
    inorderTraversal(root);
    return 0;
}