title: 'future' is not a member of 'std'
body: <p>I would like to know why my compiler complains when I test the following code :</p>
  
  <pre><code>int main(int argc, char**) {    
  ...
  std::future&lt;int&gt; result( std::async([](int m, int n) { return m + n;} , 2, 4));
  ...
  return 0;
  }
  </code></pre>
  
  <p>It gives: error: ‘future’ is not a member of ‘std’</p>
  
  <p>I have  gcc (Ubuntu/Linaro 4.7.3-2ubuntu1~12.04) 4.7.3.</p>
  
  <p>Thanks!</p>