c++ - 如何将我的类对象插入到我的非 STL 列表中？

Question

我已经为这个任务工作了一段时间，并且很难插入到我的非 STL 列表中。该代码将成功编译，但每次插入我的列表时都会出现段错误。下面是一些相关的代码。

tripper.h:

class adjNode
{
  public:
    int vertex;
    int weight;
    adjNode(int v, int w) : vertex(v), weight(w) { }
    adjNode() { }
};

tripper.cpp:

Tripper::Tripper(Road *roads, int numRoads, int size)
{
  List <adjNode> adjList[numRoads];

  for (int i=0; i<numRoads; i++) //Doesn't work with either line
  {
    adjList[roads[i].city1].push_back(adjNode(roads[i].city2, roads[i].distance));
    //adjList[0].push_back(adjNode(2, 15)); //Really it's nothing but 3 integers involved
  }
  for (int i=0; i<9; i++)
  {
    for (List<adjNode>::iterator itr = adjList[i].begin(); itr != adjList[i].end(); itr++)
    {
      cout << "There is an edge going from " << i << " to " << (*itr).vertex;
      cout << " with a weight of " << (*itr).weight << endl;
    }
  }
} // Tripper()

list.h:

void push_back( const Object & x )
{ 
  insert( end( ), x ); 
}
iterator insert( iterator itr, const Object & x )
{
    Node *p = itr.current;
    theSize++;
    return iterator( p->prev = p->prev->next = new Node( x, p->prev, p ) );
}

节点

 struct Node { 
   Object data; 
   Node *prev; 
   Node *next; 
   Node( const Object & d = Object( ), Node * p = NULL, Node * n = NULL ) 
        : data( d ), prev( p ), next( n ) 
   {
   } 
 };

Answer 1

返回迭代器( p->prev = p->prev->next = new Node( x, p->prev, p ) );

如果 p->prev 为 NULL，此行将崩溃。