Shared string in C++ ?

Question

Which "shared string" implementation for C++ would you recommend?

(Sorry if I missed a similar question. I had a look but could not find any)

Answer 1

I would use the STL: std::string and std::wstring.

ONLY if you need something more fancy you could used the smart pointers to wrap your own implementation. These smart pointers are present in the new C++ STL or boost.

• boost::shared_ptr for example if you use it inside a DLL
• boost::intrusive_ptr works over DLL boundaries.

EDIT: Like remarked in the comments STL strings are not guaranteed to be immutable by nature. If you want them to be so, use the const specifier.

Answer 2

I recommend starting with the standard strings, std::string and std::wstring.

However, there's one caveat:

Neither of the two string classes enforces a particular encoding. If you want your application to behave well when dealing with other locales or other languages than English, you should either start with std::wstring, or use something like UTF8-CPP which lets you deal with UTF-8 strings.

As Joel Spolsky pointed out, you have to know which encoding your strings are in to handle them correctly.

Answer 3

std::(w)string can be shared, but this is not mandated by the standard. QString uses an atomic refcount for sharing.