Best way to represent Nullable member in C++? [duplicate]

You could look into Boost.Optional:

struct Person
{
  std::string               Name;
  DateTime                  Birth;
  boost::optional<DateTime> Death;
  //...
};

• Your Death is “uninitialised” at first.
• You can then assign a value to it with =, like Death = myDateTime.
• When Death.is_initialized(), you can use Death.get().
• Uninitialise it again with Death.reset().

For simple cases like this, though, it’s usually considered more coherent to just pick your own blatant sentinel value like, say, a DateTime of “0000-00-00 00:00:00”.