Create a maze of Nodes from string file c++

Question

I have class Node as defined by:

class Node
{
   public:
      Node(string newName);
      Node();
      void setNodeName(string newName);
      string getNodeName();
      void attachNewNode(Node *newNode, int direction);
      Node *getAttachedNode(int direction);
   private:
      string name;
      Node *attachedNodes[4];
};

Node::Node(string newName)
{
   name = newName;
}

Node::Node()
{};

void Node::setNodeName(string newName)
{
   name = newName;
}

string Node::getNodeName()
{
   return name;
}

void Node::attachNewNode(Node *newNode, int direction)
{
   attachedNodes[direction] = newNode;
}

Node* Node::getAttachedNode(int direction)
{
   return attachedNodes[direction];
}

I have a file Maze1.txt:

9
A1
C3
A1 A2 B1 * *
A2 * B2 A1 *
A3 * B3 * *
B1 * * * A1
B2 B3 C2 * A2
B3 * * B2 A3
C1 C2 * * *
C2 C3 * C1 B2
C3 * * C2 *

Where 9 is the number of nodes to be created, A1 is the node we will begin navigation from, C3 is the node we will try to find a path to, and the following lines represent the nodes themselves and the pointers they have associated with them. For example:

A1 A2 B1 * *

represents node A1 has pointers to node A2 in the north, B1 in the east, null in the south, and null in the west.

A2 * B2 A1 *

represents node A2 has pointers to node null in the north, B2 in the east, A1 in the south, and null in the west.

I am trying to create a function that "builds" a "maze" of nodes. The following will set private variable Nodes startNode and endNode to their respective nodes and numNodes to the number of nodes as given by the file.

How can I process the string data to create Nodes for all the Node titles and then assign pointers where appropriate. Trying:

ifstream instream;
instream.open("Maze1.txt");
string line;
string data;
int numLines = 1;
int numNodes;
Node startNode();
Node endNode();

while(getline(instream, line))
{
   istringstream iss(line);
   data += line + "\n";
   iss.clear();

   if(numLines == 1)
   {
      istringstream buffer(line);
      buffer >> numNodes;
   }
   if(numLines == 2)
      Node startNode(line);
   if(numLines == 3)
      Node endNode(line);

   if(numLines > 3)
   {
      Node temp(line.substr(0,2));
      rooms.push_back(temp);
   }

   iss.clear();
   numLines++;
}

This will create and fill a vector of nodes each named the first node mentioned in each string line of the file. Following this loop, I need to run through another loop looking at each piece of the string and assign pointers to the appropriate Node in the vector. Trying:

ifstream repeat;
repeat.open(filename);
numLines = 1;
skipBlanks = 1;
int roomNum = 0;

while(getline(repeat, line))
{
   if(line.empty())
   {}
   else
   {
      istringstream iss(line);

      if(numLines == 1)
         skipBlanks++;
      if(numLines == 2)
         skipBlanks++;
      if(numLines == 3)
         skipBlanks++;

      if(numLines > 3 && skipBlanks > 3)
      {
         int first = line.find(" ", 0);
         int second = line.find(" ", first + 1);
         int third = line.find(" ", second + 1);
         int fourth = line.find(" ", third + 1);

         for(int i = 0; i < rooms.size(); i++)
         {
            if(rooms[i].getNodeName() == line.substr(first+1,2))
               rooms[roomNum].attachNewNode(rooms[i],1);
            if(rooms[i].getNodeName() == line.substr(second+1,2))
               rooms[roomNum].attachNewNode(rooms[i],2);
            if(rooms[i].getNodeName() == line.substr(third+1,2))
               rooms[roomNum].attachNewNode(rooms[i],3);
            if(rooms[i].getNodeName() == line.substr(fourth+1,2))
               rooms[roomNum].attachNewNode(rooms[i],4);
         }
      }

      roomNum++;
      numLines++;
      iss.clear();
   }
}

However, I am given compilation errors for each of the attachNewNode(Node *newNode, int direction) function calls.

error: no matching function for call to ‘Node::attachNewNode(__gnu_cxx::__alloc_traits<std::allocator<Node> >::value_type&, int)’

rooms[roomNum].attachNewNode(rooms[i],1);
                                       ^
note: candidate is:
note: void Node::attachNewNode(Node*, int) 
 void Node::attachNewNode(Node *newNode, int direction)
  ^
note:   no known conversion for argument 1 from '__gnu_cxx::__alloc_traits<std::allocator<Node> >::value_type {aka Node}’ to ‘Node*’

What does this mean? And how can I correct my assigning of pointers?

Answer 1

Without reading your complete code: The error says, that Node::attachNewNode expects a pointer to a Node but you are giving him a Node itself. This particular problem can be solved by changing your call from

     for(int i = 0; i < rooms.size(); i++)
     {
        if(rooms[i].getNodeName() == line.substr(first+1,2))
           rooms[roomNum].attachNewNode(rooms[i],1);
        if(rooms[i].getNodeName() == line.substr(second+1,2))
           rooms[roomNum].attachNewNode(rooms[i],2);
        if(rooms[i].getNodeName() == line.substr(third+1,2))
           rooms[roomNum].attachNewNode(rooms[i],3);
        if(rooms[i].getNodeName() == line.substr(fourth+1,2))
           rooms[roomNum].attachNewNode(rooms[i],4);
     }

to

     for(int i = 0; i < rooms.size(); i++)
     {
        if(rooms[i].getNodeName() == line.substr(first+1,2))
           rooms[roomNum].attachNewNode(&rooms[i],1);
        if(rooms[i].getNodeName() == line.substr(second+1,2))
           rooms[roomNum].attachNewNode(&rooms[i],2);
        if(rooms[i].getNodeName() == line.substr(third+1,2))
           rooms[roomNum].attachNewNode(&rooms[i],3);
        if(rooms[i].getNodeName() == line.substr(fourth+1,2))
           rooms[roomNum].attachNewNode(&rooms[i],4);
     }

I.e. you have to add a & in your four calls, in order to pass a pointer to the function instead of the object itself.