Question

Possible Duplicates:
C++, removing #include<vector> or #include<string> in class header
Forward declare an STL container?

I want to forward declare std::string, by the way, can I forward declare a struct?

Answer 1

std::string is a typedef so you cannot just forward declare it. You could look up the exact declaration, forward declare that and define the typedef yourself, but then you’d also have to forward declare char_traits and allocator. So this should might work, although it’s not supposed to*:

namespace std
{
  template< class T, class Traits, class Allocator >
  class basic_string;

  template< class T >
  struct char_traits;

  template< class T >
  class allocator;

  typedef basic_string< char, char_traits< char >, allocator< char > > string;
}

but in the end you’re probably better off including . I’m also unsure whether these declarations are exactly the same on all platforms, not to mention the problems it would cause should the declaration in the string header ever change.

*see comment below