Segmentation fault while trying to change game state - c++

Question

I'm making a state machine for switching game states (playing->menu->setup) in my game engine, but I'm getting a segmentation fault. I can change the game state fine from upper level, but how can I change the game state from within a game state?
Here's a minimal code example:
#include <iostream>
#include <vector>
class GameStateManager;
class GameState {
public:
GameState(GameStateManager* StateManager) {
StateManager = stateManager;
};
virtual ~GameState();
virtual void update() = 0;
GameStateManager* stateManager;
};
class GameStateManager {
public:
GameStateManager();
~GameStateManager();
void changeGameState(GameState* state) {
if(!running) {
running = true;
}
// Cleanup the current state
if(!gameStates.empty()) {
for(unsigned int i = 0; i < gameStates.size(); i++) {
delete gameStates[i];
}
gameStates.clear();
std::cout << "Cleaning up GameState" << std::endl;
}
// Store and initialize the new game state
gameStates.push_back(state);
};
void update() {
if(!gameStates.empty()) {
gameStates.back()->update();
}
};
std::vector<GameState*> gameStates;
bool running;
};
class PlayState : public GameState {
public:
PlayState(GameStateManager* stateManager) : GameState(stateManager) {};
~PlayState();
void update() override {
// On some flag, initiate the next level
nextLevel();
};
void nextLevel() {
stateManager->changeGameState(new PlayState(stateManager));
};
};
int main() {
GameStateManager stateManager;
stateManager.changeGameState(new PlayState(&stateManager));
while(stateManager.running) {
for(unsigned int i = 0; i < 10000; i++) {
std::cout << "Round: " << i << std::endl;
// Segmentation fault here
stateManager.update();
// This works
//stateManager.changeGameState(new PlayState(&stateManager));
}
stateManager.running = false;
}
return 0;
}

Answer 1

for some reason the stateManager is not being set in the GameState constructor.
so try this:
class GameState {
public:
GameState(GameStateManager* StateManager) : stateManager(StateManager)
{
};
virtual ~GameState();
virtual void update() = 0;
GameStateManager* stateManager;
};