二叉树的前序遍历，中序遍历，后序遍历（非递归方法+C语言代码）

#include<stdlib.h>
#include<stdio.h>
#include<assert.h>
#include<stdbool.h>
//定义一个二叉树结点结构体
typedef int ElemTpye;
typedef struct TreeNode
{ElemTpye data;struct TreeNode* left;struct TreeNode* right;
}TreeNode;
//创建结点
TreeNode* createTreenode(ElemTpye data)
{TreeNode* newnode = (TreeNode*)malloc(sizeof(TreeNode));assert(newnode);newnode->data = data;newnode->left = NULL;newnode->right = NULL;return newnode;
}
//非递归的前序遍历
void preOrderTraversal(TreeNode* root)
{if (root == NULL){return;}//设置一个栈TreeNode* Stack[100];int top = -1;Stack[++top] = root;while (top >= 0){TreeNode* current = Stack[top--];printf("%d ", current->data);if (current->right!=NULL){Stack[++top] = current->right;}if (current->left!=NULL){Stack[++top] = current->left;}}
}
//非递归的中序遍历
void inOrderTraversal(TreeNode* root)
{if (root == NULL){return;}//设置一个栈TreeNode* Stack[100];int top = -1;TreeNode* current = root;while (current!=NULL || top>=0){while (current != NULL){Stack[++top] = current;current = current->left;}current = Stack[top--];printf("%d ", current->data);current = current->right;}
}
//非递归的后序遍历
void postOrderTraversal(TreeNode* root)
{if (root == NULL){return;}//设置两个栈TreeNode* Stack1[100],* Stacck2[100];int top1 = -1, top2 = -1;Stack1[++top1] = root;while (top1>=0){TreeNode* current = Stack1[top1--];Stacck2[++top2] = current;if (current->left != NULL){Stack1[++top1] = current->left;}if (current->right != NULL){Stack1[++top1] = current->right;}}while (top2>=0){TreeNode* current = Stacck2[top2--];printf("%d ", current->data);}
}
// 释放二叉树内存
void freeTree(struct TreeNode* root) {if (root == NULL)return;freeTree(root->left);freeTree(root->right);free(root);
}
int main()
{TreeNode* root = NULL;root = createTreenode(1);root->left = createTreenode(2);root->right = createTreenode(3);root->left->left = createTreenode(4);root->left->right = createTreenode(5);root->right->left = createTreenode(6);root->right->right = createTreenode(7);printf("非递归前序遍历如下\n");preOrderTraversal(root);printf("\n");printf("非递归中序遍历如下\n");inOrderTraversal(root);printf("\n");printf("非递归后序遍历如下\n");postOrderTraversal(root);printf("\n");freeTree(root);return 0;
}