Using nullptr gets an error in Codeblocks IDE

Question

When using nullptr in my code, it doesn't work. Whilst there may be other threads and stuff that may explain, I've tried a couple and they didn't work well. I'm following a SFML/C++ Tutorial, and here is the code:

GameState * Game::peekState() {
  if (this - > states.empty()) return nullptr;
  return this - > states.top();
}

void Game::gameLoop() {
  sf::Clock clock;

  while (this - > window.isOpen()) {
    sf::Time elapsed = clock.restart();
    float dt = elapsed.asSeconds();

    if (peekState() == nullptr) continue;
    peekState() - > handleInput();
    peekState() - > update(dt);
    this - > window.clear(sf::Color::Black);
    peekState() - > draw(dt);
    this - > window.display();
  }
}

The error is as follows: error: 'nullptr' was not declared in this scope.

nullptr is outlined blue and showed up when I typed half of the work however.

Answer 1

nullptr is a C++11 feature. You thus need to compile your code in C++11 mode to use it. See here how to do that.