error saying class defined as public is private

Question

Making a 3D Tic Tac Toe game using class inheritance. Compiler error as follows.

line:

43 [Error] 'void CPUClass::cpu()' is private

190 [Error] within this context

Looking at my code, I've clearly defined cpu() as public. Any ideas what I'm overlooking?

#include <iostream> 
#include <time.h> //seeding random
#include <windows.h>

using namespace std;


class TTT {
      public: 
            void setup();
            void display();
            void cpu();
            void player();
            void check(int); 

      protected:
              int cp; //comp points
              int pp; //player points
              char board[9]; //board
              char board2[9];
              char board3[9];
              char xo[2]; 
              int rn; //random who goes first
              int won;//checks for win or stalemate
              int turn;//keeps track of current player
              int rc;//random comp move
              int full;//see if board is full
              int b1f; 
              int b2f;
              int b3f;


};

class CPUClass : public TTT{


      void cpu();

      };

int main(int argc, char *argv[])
{

    TTT ttt; 

    cout << "Newfangled 3D TicTacToe!" << endl; 
    cout << "~~play as though all three boards are stacked as a cube. Same rules apply.~~" << endl;

    ttt.setup();


}

void TTT::setup(){ //sets up gamespace

     won = 0;  //game not won 
     full = 0; //board is full at 9
     cp = 0;
     pp =0;
     b1f = 0;
     b2f = 0;
     b3f=0;

//the three boards:
     board[0] = '1';
     board[1] = '2';
     board[2] = '3';
     board[3] = '4';
     board[4] = '5';
     board[5] = '6';
     board[6] = '7';
     board[7] = '8';
     board[8] = '9';

     board2[0] = '1';
     board2[1] = '2';
     board2[2] = '3';  
     board2[3] = '4';
     board2[4] = '5';
     board2[5] = '6';
     board2[6] = '7';
     board2[7] = '8';
     board2[8] = '9';

     board3[0] = '1';
     board3[1] = '2';
     board3[2] = '3';
     board3[3] = '4';  
     board3[4] = '5';
     board3[5] = '6';
     board3[6] = '7';
     board3[7] = '8';
     board3[8] = '9';

     srand(time(NULL));
     rn = (rand() %2); 

     if (rn == 0){ 
            turn = 0; // comp goes first
            xo[0] = 'x'; //comp = x
            xo[1] = 'o'; //human = o
             cout << "\nYou are 'O'" << endl; 
          }else{
              turn = 1; //player goes first
              xo[0] = 'o'; //comp = o
              xo[1] = 'x'; // human = x
              cout << "\nYou are 'X'" << endl; 
              }

     display(); //send this info to display function
     }

void TTT::display(){/******you left off revising right here at 2:10******/

     cout << "" << endl; 
     for (int i = 0; i < 9; i++)
    {


        if ( (i+1) % 3 == 0 )
        {
            cout << board[i] << endl;
        }
        else 
        {

            cout << board[i] << " | ";
        }
   }

     cout << "" << endl; 
     cout << "\t";
     for (int i = 0; i < 9; i++)
         {


        if ( (i+1) % 3 == 0 )
        {

            cout << board2[i] << endl;
            cout << "\t";
        }
        else 
        {

            cout << board2[i] <<    " | "; 
        }


   }

   cout << "" << endl; 
     cout << "\t\t";
     for (int i = 0; i < 9; i++)
    {


        if ( (i+1) % 3 == 0 ) 
        {

            cout << board3[i] << endl; 
            cout << "\t\t";
        }
        else 
        {

            cout << board3[i] <<    " | ";
        }


   }
   cout << "" << endl;

    CPUClass cc;

    if (full == 27){ //if board is full
    check(won); //check if game has been won or tiedtied
        }
    else{

         if (turn%2 == 0){ 
             player();
             }else{
                 cc.cpu();
          }

         }

     }

void TTT::player(){

  int w;
  int p;
  while (won != 1) //if no one has won
  {

     cout << "Make your move: Choose a layer [top=1 middle=2 bottom=3]" << endl;
     cin>> p; 

     if (p == 1){

           cout << "Make your move: Choose a space" << endl;
           cin>>w;

           if ((board[w-1] == 'x') || (board[w-1] == 'o')){ //checks if spot is open

            cout << "\nSpace occupied, Invalid move\n";
            player();

        }else{
              board[w-1] = xo[1];//draws current players move
              turn ++;
              full ++;
              b1f++;
              display(); //go to display
              }

           }  

        else if (p == 2){

           cout << "Make your move: Choose a space" << endl;
           cin>>w;

           if ((board2[w-1] == 'x') || (board2[w-1] == 'o')){ //checks if spot is open

            cout << "\nSpace occupied, Invalid move\n";
            player();

        }else{
              board2[w-1] = xo[1];
              turn ++;
              full ++;
              b2f++;
              display(); 
              }

           }  

     else if (p == 3){

           cout << "Make your move: Choose a space" << endl;
           cin>>w;

           if ((board3[w-1] == 'x') || (board3[w-1] == 'o')){ //checks if spot is open

            cout << "\nSpace occupied, Invalid move\n";
            player();

        }else{
              board3[w-1] = xo[1];
              turn ++;
              full ++;
              b3f;
              display(); 
              }

           } 
           else{
                cout <<"Please select one of the options!\n\n" ; 
                player();
                } 

     }

  }
void TTT::cpu(){


     srand(time(NULL)); //seeds with clock
     rc = (rand() %9);
     int bc;

     if (b1f == 9){ //if a board is filled go one of the opthers
          bc = 1+(rand() %2);
      }
      else if (b3f == 9){
           bc = (rand() %2);
           }
      else if (b2f == 9){
           bc = (rand() %2);
           if (bc == 1){
                  bc = 2;
                  }
           }
      else {
           bc = (rand() %3); //randomly pick one if none are full
           }

     if (bc == 0){

     if ((board[rc] == 'x' ) || ( board[rc] == 'o')){

         cpu(); //loops and finds a new spot

         }else{
           turn++;
           full ++; 
           b1f++;
           board[rc] = xo[0]; 
           display(); 
         }

     }

     else if (bc == 1){

          if ((board2[rc] == 'x' ) || ( board2[rc] == 'o')){

         cpu(); //loops and finds a new spot

           }else{
           turn++;
           full ++; 
           b1f++;
           board[rc] = xo[0]; 
           display(); 
         }

     }

          else if (bc == 2){

               if ((board3[rc] == 'x' ) || ( board3[rc] == 'o')){

         cpu(); //loops and finds a new spot

         }else{
           turn++;
           full ++; 
           b1f++;
           board[rc] = xo[0]; 
           display(); 
         }
     }
               }

void TTT::check(int wo)// check wins
{
     //horizontal win
      if ((board[0] == 'x') && (board[1] == 'x') && (board[2] == 'x')){

                   if (rn == 0){
                          cp++;
                          }else{
                                pp++;
                                }

                   }


      if ((board[6] == 'x') && (board2[4] == 'x') && (board3[2] == 'x')){


          if (rn == 0){
                          cp++;
                          }else{
                                pp++;
                                }
          }

              wo =1;
              cout << "\nGame Over!\n" ;

              cout << "\nScore: Player - "<<pp<<" Computer - "<<cp<<"\n" ;

              if (pp == cp){ //if points are =
                     cout << "STALEMATE\n" ;
                     }
              else if (pp > cp){
                   cout << "YOU WIN\n" ;
                   }
              else if (pp < cp){
                   cout << "The computer wins\n" ;
                   }

              int c;
           cout<<"\nPlay again? [1] for yes anything else to exit\n" ;
           cin >> c;

           if (c == 1){ //if user enters 1, reset the game
                 setup();
                 }
           else{
           exit(0);

              }
     }

Answer 1

If you would like to use a member function of a class in another member function you can call the function like so:

TTT::cpu(); //replace for any calls to cc.cpu();

It is not clear from your code what purpose the CPUClass serves. What you are currently doing is you are creating a new class that inherits everything from the base class. Then you are overriding the cpu() method of the base class with a new empty method and changing its access to private.

Answer 2

methods in classes are themselves private by default unless you specify otherwise

class CPUClass : public TTT{
public:

  void cpu();

  };

Answer 3

By default, class access is private. If you want to call CPUClass::cpu() function through a CPUClass object, you need to make cpu() public:

class CPUClass : public TTT{
public:            //<<----- make below functions public
      void cpu();
};