C++ std::shared_ptr usage and information

问题:

I am trying to use std::shared_ptr in my code. I have seen there have been other questions on the subject, but I am still getting a compiler error. Have I got the right version of gcc and setup?

What I have done:

I have tried to compile my code with both headers separately — <memory> and <tr1/memory> but still get the errors below in both cases.

The version of gcc I am using is

gcc --version
gcc (GCC) 4.3.2

When I include <memory> header I use std::shared_ptr and with the <tr1/memory> header I use std::tr1::shared_ptr? Is this correct?

I have set up the shared_ptr as follows:

std::shared_ptr<A*> ptr_A = shared_ptr( new A() );

The error I get is as follows:

src/WH.cxx:156: error: 'shared_ptr' is not a member of 'std'
src/WH.cxx:162: error: 'shared_ptr' was not declared in this scope

when I try the <tr1/memory> header

src/WH.cxx:156: error: 'std::tr1' has not been declared
src/WH.cxx:162: error: 'shared_ptr' was not declared in this scope

Looks like I am not including something correctly. Any ideas?

I know the boost library has shared_ptr but these libraries are not an option for me at the moment.

EDIT: Just to add, my compiler options are as follows: g++ -O3 -g3 -m32 -fPIC -Wno-deprecated -pthread -m32 Am I missing anything?

P.S. Is there any useful literature on the std smart pointers?

回答1:

std::tr1::shared_ptr is part of the TR1 additions to the C++ STL.
With GCC, it is available either through #include <tr1/memory> (GCC 4.1) or #include <memory> (GCC 4.3)

回答2:

You were also asking for references or literature...

I found 3 articles that may help:

• An article on Smart Pointers, which is an overview good for a general understanding.
• An actual reference for std::shared_ptr.
• A great tutorial discussing every method of TR1 shared_ptr along with sample code.

Also a comment on your code example:

std::shared_ptr<A*> ptr_A = shared_ptr( new A() ); 

The template argument should be A instead of A* :

std::shared_ptr<A> ptr_A = shared_ptr( new A() ); 

回答3:

If you don't have shared_ptr in std you can use it from boost.

#include <boost/shared_ptr.hpp>

boost::shared_ptr<A> ptr_A( new A() );