Undeclared identifier error where none seems apparent - c++

Question

I am trying to implement a simple version of Conway's Game of Life which consists of a header file and three .cpp files (two for class functions, one for main). Here I have included my header files and two class function declaration files ( the compiler is having no problem with my Main.cpp file).
Game_Of_Life.h
#include <iostream>
#include <cstdlib>
#include <time.h>
using namespace std;
class cell{
public:
cell();
int Current_State(); // Returns state (1 or 0)
void Count_Neighbours(cell* A); // Counts the number of living cells in proximity w/o wraparound
void Set_Future(); // Determines the future value of state from # of neighbbours
void Update(); // Sets state to value of future state
void Set_Pos(unsigned int x, unsigned int y); // Sets position of cell in the array for use in counting neighbours
private:
int state;
int neighbours;
int future_state;
int pos_x;
int pos_y;
};
class cell_array{
public:
cell_array();
void Print_Array(); // Prints out the array
void Update_Array(); // Updates the entire array
void Set_Future_Array(); // Sets the value of the future array
private:
cell** A;
};
Cell_Class_Functions.cpp
#include "Game_Of_Life.h"
cell::cell(){
state = rand() % 2;
return;
}
void cell::Set_Future (){
if (state == 1){
if (neighbours < 2) future_state = 0;
else if (neighbours == 2 || neighbours == 3) future_state = 1;
else if (neighbours > 3) future_state = 0;
}
else{
if (neighbours == 3) future_state = 1;
}
return;
}
void cell::Update (){
state = future_state;
return;
}
int cell::Current_State (){
return state;
}
void cell::Set_Pos (unsigned int x, unsigned int y){
pos_x = x;
pos_y = y;
return;
}
void Count_Neighbours (cell* A){
neighbours = 0;
if (pos_x > 0) neighbours += A[pos_y * 10 + pos_x - 1].Current_State();
if (pos_x < 9) neighbours += A[pos_y * 10 + pos_x + 1].Current_State();
if (pos_y > 0) neighbours += A[(pos_y - 1) * 10 + pos_x].Current_State();
if (pos_y < 9) neighbours += A[(pos_y + 1) * 10 + pos_x].Current_State();
if (pos_x > 0 && pos_y > 0) neighbours += A[(pos_y - 1) * 10 + pos_x - 1].Current_State();
if (pos_x > 0 && pos_y < 9) neighbours += A[(pos_y + 1) * 10 + pos_x - 1].Current_State();
if (pos_x < 9 && pos_y > 0) neighbours += A[(pos_y - 1) * 10 + pos_x + 1].Current_State();
if (pos_x < 9 && pos_y < 9) neighbours += A[(pos_y + 1) * 10 + pos_x + 1].Current_State();
return;
}
Cell_Array_Class_Functions.cpp
#include "Game_Of_Life.h"
cell_array::cell_array(){
A = (cell**) malloc (sizeof(cell*)*100);
for (unsigned int r = 0; r < 10; r++){
for (unsigned int c = 0; c < 10; c++){
*A[r * 10 + c].Set_Pos(r,c);
}
}
return;
}
void cell_array::Update_Array(){
for (unsigned int r = 0; r < 10; r++){
for (unsigned int c = 0; c < 10; c++){
*A[r * 10 + c].Update();
}
}
}
void cell_array::Set_Future_Array(){
for (unsigned int r = 0; r < 10; r++){
for (unsigned int c = 0; c < 10; c++){
*A[r * 10 + c].Count_Neighbours(A);
*A[r * 10 + c].Set_Future();
}
}
return;
}
void cell_array::Print_Array(){
cout << "\n";
for (unsigned int r = 0; r < 10; r++){
for (unsigned int c = 0; c < 10; c++)cout << *A[r * 10 + c].Current_State() << " ";
cout << "\n";
}
return;
}
As far as I understand, since I included the header file with the class declarations, then I should be able to access the private members of the class through the previously declared functions in the class.
Essentially the Error Report Looks Like
Error C2065 'item' : undeclared identifier
This error appears for every private member called from the cell class.
What am I doing wrong?

Answer 1

Also, in your Cell_Array_Class_Functions.cpp you need to adjust your functions.
The . operator is used on objects and references.You have to deference it first to obtain a reference. That is:
(*A[r * 10 + c]).Set_Pos(r,c);
Alternatively, you can use (this is the preferred and easier to read way):
A[r * 10 + c]->Set_Pos(r,c);
The two are equivalent.

Answer 2

I don't see the word item anywhere in your code. However, you need to fix:
void Count_Neighbours (cell* A){ ... }
It should be:
void cell::Count_Neighbours (cell* A){ ... }