c++ - Adding types to the std namespace

Question

Is it acceptable to add types to the std namespace. For example, I want a TCHAR-friendly string, so is the following acceptable?

#include <string>

namespace std
{
    typedef basic_string<TCHAR> tstring;
}

Or should I use my own namespace?

Answer 1

Only specializations are allowed. So for example, you are allowed to specialize std::numeric_limits for your type. And this of course must happen in namespace std::. But your typedef isn't a specialization so that's causing undefined behavior.