std::for_each is not the algorithm you should use if you want to end the loop early. It seems you want std::find_if or something similar. You should use the algorithm that is most appropriate to your task, not just the one you're familiar with.

如果你真的，真的，真的必須盡早從算法“返回”，你可以 -

Warning: what follows is a really, really bad idea and you should virtually never do it. Indeed, looking at the code may melt your face. You have been warned!

拋出異常：

bool contains2(Iter begin, Iter end, const T& x)
{
  try {
    std::for_each(begin, end, [&x](const T& y) {
        if (x == y)
          throw std::runtime_error("something");
    });
  }
  catch(std::runtime_error &e) {
    return true;
  }
  return false;
}