5)二叉树[1]二叉树的遍历（先序、中序、后序）

#include "iostream"
using namespace std;

typedef char type;
struct bnode{
    type data;
    bnode *lchild,*rchild;
};

class tree{
public:
    tree();//初始化
    ~tree();
    void create_tree(bnode *&T);//建立二叉树
    void preorder(bnode *T);//先序遍历
    void inorder(bnode *T);//中序遍历
    void postorder(bnode *T);//后序遍历
private:
    int count;//元素个数统计
};

tree::tree()//初始化
{
    count = 0;
}

void tree::create_tree(bnode *&T)//建立二叉树
{
    type x;
    cin>>x;
    if(x=='.')T=NULL;
    else {
        T = new bnode;
        T->data = x;
        count++;
        create_tree(T->lchild);
        create_tree(T->rchild);
    }
}

void tree::preorder(bnode*T)//先序遍历
{
    if(T!=NULL)
    {
        cout<<T->data<<" ";
        preorder(T->lchild);
        preorder(T->rchild);
    }
}

void tree::inorder(bnode*T)//中序遍历
{
    if(T!=NULL)
    {
        inorder(T->lchild);
        cout<<T->data<<" ";
        inorder(T->rchild);
    }
}

void tree::postorder(bnode*T)//后序遍历
{
    if(T!=NULL)
    {
        postorder(T->lchild);
        postorder(T->rchild);
        cout<<T->data<<" ";
    }
}

tree::~tree(){}

int main()
{
    tree Tree;
    bnode *T;
    cout<<"Create Tree:";
    Tree.create_tree(T);
    cout<<"Tree finished!"<<endl;
    cout<<"preorder Tree:";
    Tree.preorder(T);
    cout<<endl;
    cout<<"inorder Tree:";
    Tree.inorder(T);
    cout<<endl;
    cout<<"postorder Tree:";
    Tree.postorder(T);
    cout<<endl;
    return 0;
}