二叉树的建立和遍历

#include<iostream>
using namespace std;
struct BTreeNode                //定义二叉树结点的数据结构
{
    int data;
    BTreeNode *leftChild;       //左子结点指针
    BTreeNode *rightChild;      //右子结点指针
};
class Btree
{
    BTreeNode *root;            //根结点的指针，没写访问权限则为默认的private
public:
    Btree()                     //构造函数
    {
        root = NULL;
    }
    void createBtree(int);
    void preOrder()                     //前序遍历方法，对外接口
    {
        preOrderTraverse(root);
        cout << endl;
    }
    void preOrderTraverse(BTreeNode *); //中序遍历具体过程
    void inOrder()                      //中序遍历方法，对外接口
    {
        inOrderTraverse(root);
        cout << endl;
    }
    void inOrderTraverse(BTreeNode *);  //中序遍历具体过程
    void postOrder()                     //后序遍历方法，对外接口
    {
        postOrderTraverse(root);
        cout << endl;
    }
    void postOrderTraverse(BTreeNode *);//后序遍历具体过程
};
void Btree::createBtree(int x)
{
    BTreeNode *newnode = new BTreeNode;
    newnode->data = x;
    newnode->leftChild = NULL;
    newnode->rightChild = NULL;
    if(NULL == root)    //如果没有根结点，则第一个结点就是根结点
    {
        root = newnode;
    }
    else                //根据数值大小判断是左子结点还是右子结点
    {
        BTreeNode *father;
        BTreeNode *current = root;
        while(current != NULL)   //找到要插入newnode的节点指针
        {
            father = current;
            if(current->data > x)
            {
                current = current->leftChild;
            }
            else
            {
                current = current->rightChild;
            }
        }
        //newnode插入到father结点的左（或右）子结点位置
        if(father->data > x)
        {
            father->leftChild = newnode;
        }
        else
        {
            father->rightChild = newnode;
        }
    }
}
void Btree::preOrderTraverse(BTreeNode *root)
{
    if(root)
    {
        cout << root->data << " ";
        preOrderTraverse(root->leftChild);
        preOrderTraverse(root->rightChild);
    }
}
void Btree::inOrderTraverse(BTreeNode *root)
{
    if(root)
    {
        inOrderTraverse(root->leftChild);
        cout << root->data << " ";
        inOrderTraverse(root->rightChild);
    }
}
void Btree::postOrderTraverse(BTreeNode *root)
{
    if(root)
    {
        postOrderTraverse(root->leftChild);
        postOrderTraverse(root->rightChild);
        cout << root->data << " ";
    }
}
int main()
{
    Btree A;
    int arr[]={7, 4, 1, 5, 12, 8, 13, 11};
    //排序二叉树：左子结点<根节点<右子节点
    cout << "建立排序二叉树: ";
    int cnt = sizeof(arr) / sizeof(int);
    for(int i = 0; i < cnt; i++)
    {
        cout << arr[i] << " ";
        A.createBtree(arr[i]);
    }
    cout << endl;
    cout << "前序遍历: ";
    A.preOrder();
    cout << "中序遍历: ";
    A.inOrder();
    cout << "后序遍历: ";
    A.postOrder();
    return 0;
}

建立排序二叉树： 7 4 1 5 12 8 13 11
前序遍历：7 4 1 5 12 8 11 13
中序遍历：1 4 5 7 8 11 12 13
后序遍历：1 5 4 11 8 13 12 7