title: Using nullptr gets an error in Codeblocks IDE
body: <p>When using <code>nullptr</code> 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: </p>
  
  <pre><code>GameState * Game::peekState() {
    if (this - &gt; states.empty()) return nullptr;
    return this - &gt; states.top();
  }
  
  void Game::gameLoop() {
    sf::Clock clock;
  
    while (this - &gt; window.isOpen()) {
      sf::Time elapsed = clock.restart();
      float dt = elapsed.asSeconds();
  
      if (peekState() == nullptr) continue;
      peekState() - &gt; handleInput();
      peekState() - &gt; update(dt);
      this - &gt; window.clear(sf::Color::Black);
      peekState() - &gt; draw(dt);
      this - &gt; window.display();
    }
  }
  </code></pre>
  
  <p>The error is as follows: error: 'nullptr' was not declared in this scope.</p>
  
  <p><code>nullptr</code> is outlined blue and showed up when I typed half of the work however.</p>