Question

I encountered this problem when implementing a class:

class Cell {
     bool isAlive;
     int numNeighbours;
     //...omit irrelavent private members



     public:
         Cell();  // Default constructor
         ~Cell(); // Destructor


      void setLiving();   

     ....         
    };
    void Cell::setLiving(){
         isAlive=true;
       }


 class Grid{...
  friend std::ostream& ::operator(std::ostream& out, const Grid &g);
  };//...omit

 std::ostream& ::operator<<(std::ostream &out, const Grid &g){
 int i,j;
 for(i=0;i<g.gridSize;i++){
   for(j=0;j<g.gridSize;j++){
         if(**g.theGrid[i][j].isAliv*e*) out<<"X";
         else out<<"_";
    }
    out<<endl;
   }
    return out;
  }

The complier said that “isAlive” is a private member so I can’t call it that way
I think the problem is at “g.theGrid[i][j].isAlive”
I tried to friend class Grid but it didnt help

Answer 1

You mentioned operator<< — it’s most likely a free function, so it needs to be declared as friend to be able to access private members.

class Cell {
    friend std::ostream& operator<<(std::ostream&, const Grid&);
    // ...
};