My object is being destructed right after being constructed - c++

Question

I'm trying to construct a two-dimensional boolean array with a class I've created called Grid. The Grid object is a private member class of another class called GameOfLife. Whenever I create a GameOfLife object with the parameters belove, the Grid object first gets created with the default constructor, then it gets created again with the constructor with parameters, and then for some reason Grid's deconstructor runs and deletes everything ? I'm really out of ideas :p I'm running MinGW GCC on Eclipse Luna.
Main.cpp
const int HEIGHT = 25;
const int WIDTH = 25;
#include <iostream>
#include "GameOfLife.h"
int main(int argc, const char * argv[]) {
GameOfLife game = GameOfLife(HEIGHT, WIDTH, false);
game.play();
return 0;
}
Grid.h
#ifndef __Game_Of_Life__Grid__
#define __Game_Of_Life__Grid__
#include <stdio.h>
class Grid {
public:
Grid(int y, int x, bool state);
Grid();
void allocate(int x, int y, bool state);
void deallocate();
void set(int x, int y, bool state);
bool get(int x, int y);
void setAll(bool state);
void switchBoards();
~Grid();
private:
bool ** oldGeneration;
bool ** newGeneration;
int height;
int width;
};
#endif /* defined(__Game_Of_Life__Grid__) */
Grid.cpp
#include "Grid.h"
Grid::Grid(int y, int x, bool state) {
allocate(x, y, state);
}
void Grid::allocate(int x, int y, bool state) {
height = y;
width = x;
oldGeneration = new bool*[height];
newGeneration = new bool*[height];
for (int i = 0; i < height; i++) {
oldGeneration[i] = new bool[width];
newGeneration[i] = new bool[width];
}
}
Grid::~Grid() {
deallocate();
}
void Grid::switchBoards() {
bool ** temp = oldGeneration;
oldGeneration = newGeneration;
newGeneration = temp;
delete temp;
}
bool Grid::get(int x, int y) {
return oldGeneration[y][x];
}
void Grid::set(int x, int y, bool state) {
newGeneration[y][x] = state;
}
void Grid::deallocate() {
if (oldGeneration != NULL || newGeneration != NULL) {
for (int i = 0; i < height; i++) {
delete [] oldGeneration[i];
delete [] newGeneration[i];
}
delete [] oldGeneration;
delete [] newGeneration;
}
return;
}
Grid::Grid() {
oldGeneration = NULL;
newGeneration = NULL;
width = 0;
height = 0;
}
void Grid::setAll(bool state) {
for (int i = 0; i < height; i++) {
for (int n = 0; n < width; n++) {
newGeneration[i][n] = state;
}
}
}
GameOfLife.h
#ifndef __Game_Of_Life__GameOfLife__
#define __Game_Of_Life__GameOfLife__
#include <stdio.h>
#include "Grid.h"
#include <iostream>
class GameOfLife {
private:
Grid board;
public:
GameOfLife(int y, int x, bool state);
GameOfLife();
~GameOfLife();
void play();
void welcome();
void makeBoard();
void updateBoard();
int findAliveNeighbours(int x, int y);
};
#endif /* defined(__Conway__GameOfLife__) */
GameOfLife.cpp
#include "GameOfLife.h"
const int WIDTH = 100;
const int HEIGHT= 75;
GameOfLife::GameOfLife(int y, int x, bool state) {
board = Grid(y, x, state);
}
GameOfLife::GameOfLife() {
board = Grid();
}
GameOfLife::~GameOfLife() {
board.deallocate();
}
void GameOfLife::play() {
welcome();
makeBoard();
for (int i = 0; i < HEIGHT; i++) {
for (int n = 0; n < WIDTH; n++) {
std::cout << board.get(n,i) << " ";
}
std::cout << std::endl;
}
updateBoard();
std::cout << std::endl;
for (int i = 0; i < HEIGHT; i++) {
for (int n = 0; n < WIDTH; n++) {
std::cout << board.get(n,i) << " ";
}
std::cout << std::endl;
}
}
void GameOfLife::makeBoard() {
int x1,x2,x3,x4, y1,y2,y3,y4;
x1 = 10; y1 = 10;
x2 = 10; y2 = 11;
x3 = 10; y3 = 12;
x4 = 11; y4 = 13;
int x5 = 0; int y5 = 0;
board.set(x1, y1, true);
board.set(x2, y2, true);
board.set(x3, y3, true);
board.set(x4, y4, true);
board.set(x5, y5, true);
}
void GameOfLife::welcome() {
std::cout << "Welcome to Conway's Game Of Life"
<< std::endl;
}

Answer 1

GameOfLife::GameOfLife(int y, int x, bool state) {
// board is a member variable that gets initialized
// with the default constructor.
// Then it gets replaced by assignment with a different
// Grid object. The temporary object gets deleted at
// the end of the line.
board = Grid(y, x, state);
}
Change the implementation to:
GameOfLife::GameOfLife(int y, int x, bool state) : board(y, x, state) {}
Similarly, change the default constructor to:
GameOfLife::GameOfLife() {}
The more important problem that needs to be fixed is that you are breaking The Rule of Three.
You need to add proper implementations of the copy constructor and the copy assignment opertor in Grid.
The other, and better, option is to change the internal data of Grid to
std::vector<std::vector<bool>> oldGeneration;
std::vector<std::vector<bool>> newGeneration;
Then, the compiler generated copy constructor and copy assignment operator will be good enough.