二叉树先序，中序，后序遍历非递归实现

#include <stdio.h>#include <malloc.h>#include <stdlib.h>#include <queue>#include <stack>#include <iostream>using namespace std;typedef struct BiTNode{char data;BiTNode *lchild, *rchild;}BiTNode,*BiTree;void CreateBiTree(BiTree &T)//建树，按先序顺序输入节点{char ch;scanf("%c",&ch);if(ch==' '){T=NULL;return;}else{T=(BiTree)malloc(sizeof(BiTNode));if(!T)exit(1);T->data=ch;CreateBiTree(T->lchild);CreateBiTree(T->rchild);}}void InOrderTraverse(BiTree T)//非递归中序遍历{stack<BiTree> Stack;if(!T){printf("空树！\n");return;}while(T || !Stack.empty()){while(T){Stack.push(T);T=T->lchild;}T=Stack.top();Stack.pop();printf("%c",T->data);T=T->rchild;}                                                                                                                                   }void PreOrderTraverse(BiTree T)//非递归先序遍历{stack<BiTree> Stack;if(!T){printf("空树！\n");return;}while(T || !Stack.empty()){while(T){Stack.push(T);printf("%c",T->data);T=T->lchild;}T=Stack.top();Stack.pop();         T=T->rchild;}                                                                                                                                   }void PostOrderTraverse(BiTree T)//非递归后序遍历,用一个标记标记右子树是否访问过{int flag[20];stack<BiTree> Stack;if(!T){printf("空树！\n");return;}while(T){Stack.push(T);flag[Stack.size()]=0;T=T->lchild;}while(!Stack.empty()){T=Stack.top();while(T->rchild && flag[Stack.size()]==0){flag[Stack.size()]=1;T=T->rchild;while(T){Stack.push(T);flag[Stack.size()]=0;    T=T->lchild;}}T=Stack.top();printf("%c",T->data);    Stack.pop();}                                                                                                                                   }void main(){  BiTree T;CreateBiTree(T);PreOrderTraverse(T);printf("\n");         InOrderTraverse(T);printf("\n");PostOrderTraverse(T);printf("\n");}