二叉树的非递归先序，中序，后序遍历

#include <iostream>
#include <stack>

using namespace std;

typedef struct node
{
char data;
struct node *lchild;
struct node *rchild;
} BiNode, *BiTree;

//先序递归创建树，这里注意参数的类型，T的类型是 "*&" ,如果是 "**" 代码稍加改动就OK...
void createTree(BiTree &T)
{
char ch;
cin.get(ch).get();
//过滤输入流中每次回车产生的回车符
if (ch==' ')
T = NULL; //这里首先判断是不是空格，如果是，则为该节点赋NULL
else
{
T = (BiTree)malloc(sizeof(BiNode));
T->data = ch;
createTree(T->lchild);
createTree(T->rchild);
}
}

void preOrderNoRe(BiTree T) // 前序遍历
{
if( T == NULL)
{
return ;
}
stack<BiTree> s;
BiTree p = NULL;
p = T;
while( p != NULL || !s.empty())
{
while (p != NULL)
{
cout<< p->data <<" ";
s.push(p);
p = p->lchild;
}

if(!s.empty())
{
p = s.top();
s.pop();
p = p->rchild;
}
}
}

void inOrderNoRe(BiTree T) //中序遍历
{
if( T == NULL)
{
return ;
}
stack<BiTree> s;
BiTree p = NULL;
p = T;
while(p != NULL || !s.empty())
{
while (p != NULL)
{
s.push(p);
p = p->lchild;
}
if (!s.empty())
{
p = s.top();
s.pop();
cout << p->data <<" "; p = p->rchild;
}
}
}

void postOrderNoRe(BiTree T) //后序遍历
{
if( T == NULL)
{
return ;
}

BiTree p = NULL;
stack<BiTree> s;
p = T;
int Tag[200]; // 栈，用于标识从左（0）或右（1）返回
int top = -1;
while ( p != NULL || !s.empty())
{
while( p != NULL)
{
s.push(p);
Tag[++top] = 0;
p = p->lchild;
}

while ( !s.empty() && Tag[top] == 1)
{
p = s.top();
s.pop();
cout<< p->data << " "; --top; // 出栈
}
if (!s.empty())
{
Tag[top] = 1; //设置标记右子树已经访问
p = s.top();
p = p->rchild;
}
else
{
break;
}
}
}

int main()
{
cout<<"Enter char one by one"<<endl;
BiNode *T;
createTree(T);
cout<<endl;

cout<<"preOrderNoRe: ";
preOrderNoRe(T);
cout<<endl;
cout<<"inOrderNoRe: ";
inOrderNoRe(T);
cout<<endl;

cout<<"postOrderNoRe: ";
postOrderNoRe(T);
cout<<endl;

system("pause");
return 0;
}