Why is there a different string class in every C++ platform out there?

Question

While I like programming in C++, I hate the idea of:
std::basic_string vs QString vs wxString vs .............
Doesn't the standard string class satisfy the needs for these frameworks? I mean what is wrong with the standard string class?!

Just to emphasize, that below is the important question:
Do you learn "the" string class of the framework in every framework you are going to work with? would you instead stick to the standard string class by trying to adapt it everywhere?

Thanks...

Answer 1

The reason for multiple string classes is that the C++ standard was finalized fairly late (in 1998); it then took some time until all systems actually provided a correct C++ library. By that time, all these competing string classes where already written.

In addition, in some cases, people want to inherit from a single base class, which std::string wouldn't do.

Answer 2

IMO, std::string isn't old enough to be widespread (Qt and wxWidgets are older than the STL, or at least older than widely available stable and working STLs). Also, std::string is sadly not the best string class there is for everyone, and other frameworks have other needs.

Note! The paragraph below slightly incorrect, but kept to make sense of comments.

For instance, C++ STL's is very resource constrained, whereas the Qt string class offer lots of goodies that a committe would never agree on, especially as some want it to be easily implementable on embedded systems and the like.