c++ - 使用 vector 的 vector 对网络建模

Question

我正在尝试使用 C++ 为网络建模。我有一个名为 NetworkConnection 的结构:

struct NetworkConnection {
  int i, j, weight;
}

我有一个名为 Network 的类

class Network {
  public:
    std::vector<NetworkConnection> connections_for(int i) {
      return connections[i];
    }
    void connect(int i, int j, int weight) {
      NetworkConnection connection;
      connection.i = i;
      connection.j = j;
      connection.weight = weight;
      connections[i].push_back(connection)
    }
  private:
    std::vector< std::vector<NetworkConnection> > connections;
}

现在我的问题是调用 connections_for(i) 时出现段错误，特别是在复制构造函数中。然而，令人困惑的是，段错误的确切情况在应用程序的运行之间有所不同。我试过像这样使用指针 vector 和指针 vector vector :

std::vector< std::vector<NetworkConnection> * > connections;
std::vector< std::vector<NetworkConnection *> > connections;

对界面进行了适当的调整，但并没有解决问题。现在我不知道如何解决这个问题。

我在这里做错了什么？或者，您将如何使用与上述类似的接口(interface)在 C++ 中为网络建模？

Answer 1

您想使用 map :

class Network {
  public:
    std::vector<NetworkConnection> connections_for(int i) {
      return connections[i];
    }
    void connect(int i, int j, int weight) {
      NetworkConnection connection;
      connection.i = i;
      connection.j = j;
      connection.weight = weight;
      connections[i].push_back(connection);
    }
  private:
    std::map<int, std::vector<NetworkConnection> > connections;
};

您甚至可能想使用 map 中的 map :

class Network {
  public:
    std::map<int, NetworkConnection> &connections_for(int i) {
      return connections[i];
    }
    void connect(int i, int j, int weight) {
      NetworkConnection connection;
      connection.i = i;
      connection.j = j;
      connection.weight = weight;
      std::map<int, NetworkConnection> &map = connections_for(i);
      map[j] = connection;
    }
  private:
    std::map<int, std::map<int, NetworkConnection> > connections;
};