template<class Elem>
class BinNode//Binary tree node abstract class.
{
public:
virtual Elem& val() = 0;//return the node's element;
virtual void setVal(const Elem& ) = 0;//set the node's element;
virtual BinNode* left() const = 0;//return the node's left child;
virtual BinNode* right() const = 0;//return the node's right child;
virtual void setLeft(BinNode*) = 0;//set the node's left child's element;
virtual void setRight(BinNode*) = 0;//set the node's right child's element;
};
template<class Elem>
class BinNodePtr:public BinNode<Elem>
{
public:
Elem ele;//the content of the node
BinNodePtr<Elem>* lc;//the node's left child
BinNodePtr<Elem>* rc;//the node's right child
public:
static int now_on;//the node's identifier
BinNodePtr(){lc = rc = NULL;ele = 0;};//the constructor
~BinNodePtr(){};//the destructor
void setVal(const Elem& e){this->ele = e;};
Elem& val(){return ele;}//return the element of the node
inline BinNode<Elem>* left()const//return the node's left child
{
return lc;
}
inline BinNode<Elem>* right()const//return the node's right child
{
return rc;
}
void setLeft(const Elem& e){lc->ele = e;}//to set the content of the node's leftchild
void setRight(const Elem& e){rc->ele = e;}//to set the content of the node's rightchild
};
int main()
{
BinNodePtr<int> root;//initiate a variable//the error is here.
BinNodePtr<int> subroot = &root;//initiate a pointer to the variable
}
当我构建它时,编译器告诉我“无法实例化抽象类”。错误在 BinNodePtr root 处;我不是在实例化抽象类,而是从抽象类派生的类。我该如何解决它?
最佳答案
在抽象类中。
virtual void setLeft(**BinNode***) = 0;//set the node's left child's element;
virtual void setRight(**BinNode***) = 0;//set the node's right child's element;
在派生类中
void setLeft(const **Elem**& e){lc->ele = e;}
void setRight(const **Elem**& e){rc->ele = e;}
函数签名不匹配..
关于c++ - 如何实例化从抽象类派生的类,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/22496148/