C++写二叉树

在代码中都是使用的是递归来遍历二叉树，在这里面的代码中主要测试的是二叉树的插入和遍历insert()和preOrder(),inOrder(),postOrder();

#include<iostream>using namespace std;template <class Type> class BinaryTree;template <class Type> class BinTreeNode {    friend class BinaryTree<Type>;public:    BinTreeNode() :leftChild(NULL), rightChild(NULL) {}    BinTreeNode(Type item, BinTreeNode<Type> *left = NULL,        BinTreeNode<Type> *right = NULL) :        data(item), leftChild(left), rightChild(right) {}    Type GetData()const { return data; }    BinTreeNode<Type> *GetLeft()const { return leftChild; }    BinTreeNode<Type> *GetRight()const { return rightChild; }    void setData(const Type &item) { data = item; }    void SetLeft(BinTreeNode <Type>*L) { leftChild = L; }    void SetRight(BinTreeNode<Type> *R) { rightChild = R; }private:    BinTreeNode<Type> *leftChild, *rightChild;    Type data;};template<class Type> class BinaryTree {public:    BinaryTree() :root(NULL) {}    BinaryTree(Type value) :RefValue(value), root(NULL) {}    virtual ~BinaryTree() { destroy(root); }    virtual int IsEmpty() {        return root == NULL ? 1 : 0;    }    virtual BinTreeNode<Type> *Parent(BinTreeNode<Type>* current) {        return root == NULL || root == current ? NULL : Parent(root, current);    }    virtual BinTreeNode <Type> *LeftChild(BinTreeNode<Type>*current) {        return current != NULL ? current->leftChild : NULL;    }    virtual BinTreeNode<Type> *RightChild(BinTreeNode<Type> *current) {        return current != NULL ? current->rightChild : NULL;    }    bool Insert(const Type &item);//  virtual int Find(const Type &item)const;    BinTreeNode<Type> *GetRoot()const { return root; }    friend istream & operator >> (istream &in, BinaryTree<Type> &Tree);    friend ostream & operator << (ostream &out, BinaryTree<Type> &Tree);public:    BinTreeNode<Type> *root;    Type RefValue;    BinTreeNode<Type> *Parent(BinTreeNode<Type>*start,        BinTreeNode<Type>*current);     void preOrder(BinTreeNode<Type> *current);     void inOrder(BinTreeNode<Type> *current);    void postOrder(BinTreeNode<Type> *current);    void destroy(BinTreeNode<Type> *current);};template<class Type> void BinaryTree<Type>::destroy(BinTreeNode<Type>*current) {    if (current != NULL) {        destroy(current->leftChild);        destroy(current->rightChild);        delete current;    }}template<class Type> bool BinaryTree<Type>::Insert(const Type &item) {    if (root == NULL) {        root = new BinTreeNode<Type>(item);    }    else {        BinTreeNode<Type> *parent = NULL;        BinTreeNode<Type>  *p = root;        while (p != NULL) {            if (item<p->data) {                parent = p;                p = p->leftChild;            }            else if (item>p->data) {                parent = p;                p = p->rightChild;            }            else {                return false;            }        }        if (item<parent->data)            parent->leftChild = new BinTreeNode<Type>(item);        else            parent->rightChild = new BinTreeNode<Type>(item);    }    return true;}//寻找parent节点template <class Type> BinTreeNode <Type> * BinaryTree <Type> ::Parent(BinTreeNode    <Type> * start, BinTreeNode <Type> *current) {    if (start == NULL) return NULL;    if (start->leftChild == current ||        start->rightChild == current)        return start;    BinTreeNode <Type> *p;    if ((p = Parent(start->leftChild, current))        != NULL) return p;    else return Parent(start->rightChild, current);}//将二叉树输出template <class Type> void BinaryTree<Type>::preOrder(    BinTreeNode <Type> *current){    if (current != NULL) {        cout << current->data << ' ';        preOrder(current->leftChild);        preOrder(current->rightChild);    }}template <class Type> void BinaryTree<Type>::inOrder(BinTreeNode <Type> *current) {    if (current != NULL) {        inOrder(current->leftChild);        cout << current->data << ' ';        inOrder(current->rightChild);    }}template <class Type> void BinaryTree<Type>::postOrder(BinTreeNode <Type> *current) {    if (current != NULL) {        postOrder(current->leftChild);        postOrder(current->rightChild);        cout << current->data << ' ';    }}template <class Type> istream & operator >> (istream & in, BinaryTree<Type> &Tree) {    Type item;    cout << "构造二叉树 : \n ";    cout << "输入数据 ( 用 " << Tree.RefValue        << "结束 ): ";    in >> item;    while (item != Tree.RefValue) {        Tree.Insert(item);        cout << "输入数据 ( 用 " << Tree.RefValue            << "结束 ): ";        in >> item;    }    return in;}template <class Type> ostream & operator << (ostream &out, BinaryTree<Type> &Tree) {    out << "二叉树的前序遍历.\n";    Tree.Traverse(Tree.root, out);    out << endl;    return out;}int main() {    BinaryTree<int> BT;    BT.Insert(4);    BT.Insert(3);    BT.Insert(5);     BT.Insert(2);    BT.Insert(6);     cout << BT.GetRoot()->GetData() << endl;    BT.preOrder(BT.GetRoot());     cout << endl;    BT.inOrder(BT.GetRoot());    cout << endl;    BT.postOrder(BT.GetRoot());    cout << endl;    getchar();    return 0;}