Why this compile error?

[Yile]

Code: Select all

#include <iostream>

using namespace std;

template <class ValueType> class ZKTreeNode{
private:
    ValueType m_value;
    ZKTreeNode<ValueType>* m_parent;
    ZKTreeNode<ValueType>* m_lch;
    ZKTreeNode<ValueType>* m_rch;
    
public:
    ZKTreeNode(){
        m_parent = NULL;
        m_lch = NULL;
        m_rch = NULL;
    }
    
    ZKTreeNode<ValueType>* parent(){
        return m_parent;
    }
    
    ZKTreeNode<ValueType>* lch(){
        return m_lch;
    }
    
    ZKTreeNode<ValueType>* rch(){
        return m_rch;
    }
    
    void setParent(ZKTreeNode<ValueType>* parent){
        m_parent = parent;
    }
    
    void setLCh(ZKTreeNode<ValueType>* lch){
        m_lch = lch;
    }

    void setRCh(ZKTreeNode<ValueType>* rch){
        m_rch = rch;
    }
    
    void setValue(ValueType& value){
        m_value = value;
    }
};

template <class ValueType> class ZKBinaryTree{
private:
    ZKTreeNode<ValueType>* m_root;
    
    void clearSubTree(ZKTreeNode<ValueType>* root){
        if(root != NULL){
            clearSubTree(root->lch());
            clearSubTree(root->rch());
            delete root;
        }
    }
    
public:
    ZKBinaryTree(){
        m_root = NULL;
    }
    
    ~ZKBinaryTree(){
        clear();
    }
    
    void clear(){
        clearSubTree(m_root);
        m_root = NULL;
    }
    
    void init(ValueType rootValue){
        clear();
        m_root = new ZKTreeNode<ValueType>;
        m_root->setValue(rootValue);
    }
    
    ZKTreeNode<ValueType>* root(){
        return m_root;
    }
};

template <class ValueType> class ZKTree : public ZKBinaryTree<ValueType>{
public:
    ZKTreeNode<ValueType>* childHead(ZKTreeNode<ValueType>* root){
        return root->lch();
    }
    
    ZKTreeNode<ValueType>* nextCousin(ZKTreeNode<ValueType>* node){
        return node->rch();
    }
    
    ZKTreeNode<ValueType>* preCousin(ZKTreeNode<ValueType>* node){
        ZKTreeNode<ValueType>* cousin;
        ZKTreeNode<ValueType>* parent = node->parent();
        cousin = (node == parent->rch())? parent: NULL;
        return cousin;
    }
    
    //新添加子节点（加在最左边） 
    void addChild(ZKTreeNode<ValueType>* root, ValueType value){
        ZKTreeNode<ValueType>* childHead = childHead(root);
        ZKTreeNode<ValueType>* newChild = new ZKTreeNode<ValueType>;
        newChild->setValue(value);
        root->setLCh(newChild);
        newChild->setParent(root);
        if(childHead != NULL){
            newChild->setRCh(childHead);
            childHead->setParent(newChild);
        }
    }
};

int main(){
    ZKTree<int> tree;
    tree.init(0);
    ZKTreeNode<int>* p = tree.root();
    tree.addChild(p, 1);
    return 0;
}

[Yile]

Oh, I've found the error. How careless I am.
I'm sorry.