类的链表问题和执行过程

#include <iostream.h>
enum {k1,k2,k3};
class data
{
public:
    data(int val):myval(val){cout << "数据结点建立\n";}
    ~data(){;}
    int compare(const data&);
    void show(){cout << myval << "\t";}
private:
    int myval;
};
int data::compare(const data& otherdata)
{
    cout << "data的compare函数\n";
    if(myval < otherdata.myval)
        return k1;
    if(myval > otherdata.myval)
        return k2;
    else
        return k3;
}
class node;
class inode;
class tnode;
class hnode;

class node
{
public:
    node(){cout << "node的构造函数\n";}
    virtual ~node(){}
    virtual node* insert(data *thedata)=0;
    virtual void show()=0;
private:
};
class inode:public node
{
public:
    inode(data* thedata,node *next);
    ~inode(){delete mynext;delete mydata;}
    virtual node* insert(data *thedata);
    virtual void show(){mydata->show();mynext->show();}
private:
    data* mydata;
    node* mynext;
};
inode::inode(data* thedata,node *next)
{
    mydata=thedata;
    mynext=next;
    cout << "inode的构造函数\n";
}
node* inode::insert(data *thedata)
{
    cout << "i的insert\n";
    int result=mydata->compare(*thedata);
    switch(result)
    {
    case k3:

    case k2:
        {
            inode* datanode=new inode(thedata,this);
            return datanode;
        }
    case k1:
        mynext=mynext->insert(thedata);
        return this;
    }
    return this;
}
class tnode:public node
{
public:
    tnode(){cout << "t的构造函数\n";}
    ~tnode(){}
    virtual node*insert(data* thedata);
    virtual void show(){}
private:

};
node* tnode::insert(data* thedata)
{
    inode* datanode=new inode(thedata,this);
    cout << "tnode的insert\n";
    return datanode;
}
class hnode:public node
{
public:
    hnode();
    ~hnode(){delete mynext;}
    virtual node*insert(data* thedata);
    virtual void show(){mynext->show();}
private:
    node* mynext;
};
hnode::hnode()
{
    mynext=new tnode;               //因为mynext被初始化为tnode；所以mynext->insert调用的是tnode的insert虚函数.
    cout << "honde的构造函数\n";
}
node* hnode::insert(data* thedata)
{
    mynext=mynext->insert(thedata);
    cout << "hnode的insert\n";
    return this;
}
class linklist
{
public:
    linklist();
    ~linklist(){delete myhead;}
    void insert(data* thedata);
    void show(){myhead->show();}
private:
    hnode *myhead;
};
linklist::linklist()
{
    myhead=new hnode;
    cout << "link的构造函数\n";
}
void linklist::insert(data* pdata)
{
    myhead->insert(pdata);
    cout << "link的insert\n";
}
int main()
{
    data* pdata;
    int val;
    linklist ll;
    for(;;)
    {
        cout << "what value?(0 to top)";
        cin >>val;
        if(!val)
            break;
        pdata=new data(val);
        ll.insert(pdata);
    }
    ll.show();
    return 0;
}