Differences between different flavours of shared_ptr

Question

Are there any differences between boost::shared_ptr, std::tr1::shared_ptr and the upcoming (in C++0x) std::shared_ptr?

Will porting from one to another have any overhead or are they basically the same?

Answer 1

According to the Boost website, the boost::shared_ptr...

...conforms to the TR1 specification, with the only exception that it resides in namespace boost instead of std::tr1.

According to the Wikipedia C++0x page

The TR1 implementation lacked certain pointer features such as aliasing and pointer arithmetic, but the C++0x version will add these.

If your code works with the TR1/Boost version, it should work with the C++0x version (but not necessarily vice versa).