從模板圖形節點類

Question

我有一個圖形類，下面簡單的實現創建子二進制樹節點類班，但我很難找出如何做到這一點。我寫了一個不完整的類，但是我收到了幾個編譯錯誤。下面是代碼：

#include <iostream> 
#include <vector> 

using namespace std; 

template <typename T> 
class GraphNode { 

public: 
    T data; 
    vector<GraphNode*> adj; 

    void Print(GraphNode<T>* node) { 

     if(!node) { 
      std::cout << "*"; 
      return; 
     } 

     std::cout << node->data << ":"; 

     for(typename vector<GraphNode<T>* >::iterator iter = adj.begin(); 
       iter != adj.end(); 
       iter++) 
     { 
      Print(iter); 
     } 
    } 
}; 

template <typename T> 
class BinaryTreeNode : public GraphNode<T> { 
    using GraphNode<T>::data; 
    using GraphNode<T>::adj; 

public: 
    BinaryTreeNode<T>* lhs; 
    BinaryTreeNode<T>* rhs; 

    BinaryTreeNode() { 
     adj.push_back(NULL); 
     adj.push_back(NULL); 

     lhs = NULL; 
     rhs = NULL; 
    } 

    BinaryTreeNode(T in_data) { 
     data = in_data; 

     adj.push_back(NULL); 
     adj.push_back(NULL); 

     lhs = NULL; 
     rhs = NULL; 
    } 


    BinaryTreeNode& operator=(const BinaryTreeNode& other) { 

     // if the other item is this, then return itself 
     if(&other != this) { 
      data = other.data; 
      // copy the vector 
      lhs = other.lhs; 
      rhs = other.rhs; 
     } 
     return *this; 
    } 

}; 

int main() { 
    BinaryTreeNode<int> node; 
    cout << 42; 
    return 0; 
} 

請注意，您試圖：

template <typename T> 
// Binary Tree Node 
class BinaryTreeNode : public GraphNode<T> { 

public: 
    BinaryTreeNode<T>* lhs; 
    BinaryTreeNode<T>* rhs; 

    BinaryTreeNode() { 
     adj.push_back(NULL); 
     adj.push_back(NULL); 

     lhs = adj[0]; 
     rhs = adj[1]; 
    } 

    BinaryTreeNode(T in_data) { 
     data = in_data; 

     adj.push_back(NULL); 
     adj.push_back(NULL); 

     lhs = adj[0]; 
     rhs = adj[1]; 
    } 


    BinaryTreeNode& operator=(const BinaryTreeNode& other) { 

     // if the other item is this, then return itself 
     if(&other != this) { 
      data = other.data; 
      // copy the vector 
      lhs = other.lhs; 
      rhs = other.rhs; 
     } 
     return *this; 
    } 

}; 

錯誤

../src/BinaryTree.h:22:3: error: ‘adj’ was not declared in this scope 
../src/BinaryTree.h:30:3: error: ‘data’ was not declared in this scope 

Answer 1

描述你的問題的根源here

This is my solution名單做一個隱含的下來投。這是不允許的。您必須使用lhs = (BinaryTreeNode*)adj[0];或其他演員（可能是dynamic_cast）。