C++ std::shared_ptr usage and information

Question

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?

You'd expect the documentation to include two things, but it doesn't: which header file to include, and which version of gcc first introduced it. gcc.gnu.org/onlinedocs/libstdc++/manual/shared_ptr.html — Mark Ransom
– Mark Ransom, Commented Nov 17, 2011 at 17:24
Depending on your version of GCC, std::shared_ptr may not exist, or may require you to specify -std=c++0x as a compiler option. — Mike Seymour
– Mike Seymour, Commented Nov 17, 2011 at 17:29
First, gcc 4.3 is very old. As of when you wrote your question, gcc 4.6 is out. Second, I believe shared_ptr is a C++11 feature, so even once you have the correct version, you will probably need to use -std=c++0x to use it. — wjl
– wjl, Commented Nov 17, 2011 at 17:32
Requests for tutorials/literature is outside the scope of this site as defined in the FAQ. — Keith Pinson
– Keith Pinson, Commented Dec 19, 2012 at 23:08
@wjl Some of us can't update compilers easily. Embedded systems often come in a collection of things, including compilers and hardware packages. Updating compiler versions can require physically changing the hardware, and that can be very expensive. — James Moore
– James Moore, Commented Aug 9, 2018 at 19:20

Alok Save · Accepted Answer · 2011-11-17 17:21:32Z

25

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)

answered Nov 17, 2011 at 17:21

Alok Save

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5 Comments

Kerrek SB Over a year ago

In GCC it depends on the presence of the -std=c++0x compiler option, too. (Or -std=c++11 from 4.7 onwards.)

MWright Over a year ago

Okay so here is my compiler options I am using. g++ -O3 -g3 -m32 -fPIC -Wno-deprecated -pthread -m32 . do I need to add -std=c++0x

Fred Larson Over a year ago

-std=c++0x isn't needed for std::tr1::shared_ptr, is it?

MWright Over a year ago

Looks Like it is needed Fred. Well for my set up. Thanks Again!

Carsten Greiner Over a year ago

With C++11 it is now std::shared_ptr

Jared Harley · Accepted Answer · 2012-12-19 23:08:14Z

10

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() );

edited Dec 19, 2012 at 23:08

Jared Harley

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answered Nov 17, 2011 at 19:13

Carsten Greiner

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2 Comments

Keith Pinson Over a year ago

Good references, even though technically that is not what this site is for.

Carsten Greiner Over a year ago

true, although he was clever enough to ask at least one stackoverflow adequate question. And honestly, when i see references from well reputated people, I usually follow and have a look - and this helps alot in the long run. cheers and merry Xmas

ronag · Accepted Answer · 2011-11-17 17:25:35Z

6

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() );

edited Nov 17, 2011 at 17:25

ronag

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answered Nov 17, 2011 at 17:19

murrekatt

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4 Comments

Fred Larson Over a year ago

Should be shared_ptr, not shred_ptr. (I know -- the error is in the question too.)

murrekatt Over a year ago

sorry :) was a bit quick here. Wanted to just point out that there shouldn't be any A* in the template.

yasouser Over a year ago

@murrekatt: The OP has said "I know the boost library has shared_ptr but these libraries are not an option for me at the moment :-(".

David Doria Over a year ago

Shouldn't it be boost::shared_ptr<A> ptr_A( new A ); (no parents after A)?

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