C++: Pointer to Vectors....

[D.P.]

This is doing my head in...


SHORT VERSION:
I want to be able to save the address of a vector in another class.


LONG VERSION:
I am moddeling a swarm of robots in a simulator. I have 2 classes- Robot and Controller. In my simulator I have a vector of each (e.g. 20 robots with 20 seperate controllers). Within the Robot class there are some vectors that store some state information, such as the UIDs of the Neighbour robots, and also distances etc. Just think of these as vectors of ints and doubles etc. These vectors are updated every step of the simulation.

I want the Controller class to be able to point to the addresses of these Neighbour UIDs and distance vectors etc. i.e. within the Controller class I want a vector of ints that point to the address of the Robot vector. Thereby as the Robot vectors are updated the Controller vectors are automatically updated without me having to send and copy the vector each step.

PROBLEM:
The addresses do not seem to be saved properly.

CODE:

class Controller {

  std:: vector<int> * NeighbourUIDs_Vector;

  void setNeighbours(std::vector<int> *NeighbourUIDs){
      NeighbourUIDs_Vector = NeighbourUIDs
      // DEBUG TEST:
      printf("BB11 %i \n", &NeighbourUIDs);      // These are equal  BB11=BB22
      printf("BB22 %i \n", &NeighbourUIDs_Vector); 
  };

  void step(){
    printf("ADDRESS1 %i \n", &NeighbourUIDs_Vector);     // Wrong address
    printf("DEBUG %i \n", NeighbourUIDs_Vector.size());     // seg faults 
  }

};

class robot{
     std:: vector<int>  NeighbourUIDs_Vector;
    // some other stuff
};

// Main code

Robot robot;       // this is actually also a vector of e.g.20 robots
Controller controller;   // this is actually also a vector of e.g.20 robots


findNeighbours(){
   // find neighbour robots, blah blah. This code works fine
   robot.NeighbourUIDs_Vector.clear();  // clear vector
   robot.NeighbourUIDs_Vector = ..... // e.g. I update the vector
}

void Init(){

  robot = new Robot();    //this is basically repeated for all robots in the robot vector
  controller = new Controller();  // same here
 
  findNeighbours();    // Assign the neighbourUIDs to each robot

   // DEBUG
   printf("AA11 %i \n", &robot.NeighbourUIDs_Vector); 
  
  controller.setNeighbours(&robot.NeighbourUIDs_Vector);   // pass the address

   // DEBUG
   printf("AA22 %i \n", &controller.NeighbourUIDs_Vector); 

  controller.step(); // will now seg Fault.
}

During the Init function I find that:
AA11 = BB11 = BB22 but when the code returns to the init function the address has changed and the address has changed and AA22 does not equal AA11 etc..

Whjat am i doing worng. What is the best way to achieve what I want. I hope you understand my goal, nothing oo difficult. I just want a pointer to the Robot vector instead of having to allocate more memory and create a new vector in Controller each and every time step.

 

[D.P.]

Any ideas?

 

[D.P.]

Ok, thanks for the help.
Yeah, my C++ is rusty after programming Java for the last 5 years!

i have it working in my test program, now to implement it in the real program.....

 

[D.P.]

I have found my actual problem in the real program. One of these reasons I hate c++!!!!

Controller was actually a subclass of SwarmController. SwarmController had a double array of size 1. I was adding 4 elements to this array. Now this array is never touched, it is not read from or anything so shouldnt have really effected the code.

But it was overwriting the memory of the pointer, altering the address so it pointed to the wrong place.

In Java I would simply get an ArrayIndexOutOfBounds error and the program would still run. I would have saved my self 6 days of hand banging.

ARRRG!