Question

我试图在c ++中实现图形。我有一个节点类，其中包含节点索引值和连接到该节点的边的列表。我还有一个edge类，其中包含edge权重以及from节点和to节点。

节点声明：

class Node {
    int value;
    vector<Edge>& edges;
public:
    Node(int input_value);
};

节点构造函数：

Node::Node(int input_value) {
  value = input_value;
  edges = {};
}

边缘声明：

class Edge: public Node {
  int value;
  // should I use int for node_from and node_to? nope
  Node node_from;
  Node node_to;
public:
  Edge(int input_value, Node node_from_in, Node node_to_in);
};

边缘构造函数：

Edge::Edge(int input_value, Node node_from_in, Node node_to_in) {
  value = input_value;
  node_from = node_from_in;
  node_to = node_to_in;
}

由于两个类是相互依赖的，所以我只转发声明class Edge;来首先声明Edge，然后在Node类中通过引用将其传递。当我跑步时，出现以下错误：

/Users/sunshenggu/Documents/Atom/Graph/Graph.cpp:4:7: error: constructor for 'Node' must explicitly initialize the reference member 'edges'
Node::Node(int input_value) {
      ^
/Users/sunshenggu/Documents/Atom/Graph/Graph.hpp:18:17: note: declared here
  vector<Edge>& edges;
                ^
/Users/sunshenggu/Documents/Atom/Graph/Graph.cpp:9:7: error: constructor for 'Edge' must explicitly initialize the base class 'Node' which does not have a default constructor
Edge::Edge(int input_value, Node node_from_in, Node node_to_in) {
      ^
/Users/sunshenggu/Documents/Atom/Graph/Graph.hpp:16:7: note: 'Node' declared here
class Node {
      ^
/Users/sunshenggu/Documents/Atom/Graph/Graph.cpp:9:7: error: constructor for 'Edge' must explicitly initialize the member 'node_from' which does not have a default constructor
Edge::Edge(int input_value, Node node_from_in, Node node_to_in) {
      ^
/Users/sunshenggu/Documents/Atom/Graph/Graph.hpp:26:8: note: member is declared here

但是当我将那些构造函数设置为默认值时，我得到了这些错误：

In file included from /Users/sunshenggu/Documents/Atom/Graph/Graph.cpp:2:
/Users/sunshenggu/Documents/Atom/Graph/Graph.hpp:20:27: error: only special member functions may be defaulted
  Node(int input_value) = default;
                          ^
/Users/sunshenggu/Documents/Atom/Graph/Graph.hpp:29:63: error: only special member functions may be defaulted
  Edge(int input_value, Node node_from_in, Node node_to_in) = default;
                                                              ^
/Users/sunshenggu/Documents/Atom/Graph/Graph.cpp:4:7: error: redefinition of 'Node'
Node::Node(int input_value) {

有人会指出我正确的方向吗？

如何在C ++中创建两个相互依赖的类？

0 个答案: