libssh2 and C++

Question

When I try to use libssh2 in my C++ class, I keep getting the following errors:

undefined reference to `libssh2_session_init_ex'
undefined reference to `libssh2_session_startup'

If I do the same thing using C, everything works fine.

Any help?

Following is the build command

g++ -Wall -g -I/libssh2-1.2.4/src -I/libssh2-1.2.4/include -L/libssh2-1.2.4/src/obj -L/openssl-0.9.8k/ -L/SecuritySDK/3.0.13/RC/LATEST/security/lib  -lssh2 -ldl -lnsl -lresolv -lhash -lhandlers -lcrypto -lssl -lz -lbpwp3   rhost.o rpipe.o rutils.o -o rpipe

following is the class member function

void rhost::InitSession()
{
    m_session = libssh2_session_init();
    if ( libssh2_session_startup(m_session, m_sock) )
    {
        fprintf (stderr, "Failure establishing SSH session\n");
        exit(-1);
    }
    return;
}

Yes platform is linux

Sounds to me like your not linking against the right libraries. — Natalie Adams, Jan 06 '11 at 13:57
Show us some of your C++ code (especially the part that calls the functions that fail to link). Also, are you using Linux? Which distro/version? — John Zwinck, Jan 06 '11 at 14:17

score 2 · Accepted Answer · edited May 23 '17 at 12:18

2

Change your call to g++ -Wall -g -I/libssh2-1.2.4/src -I/libssh2-1.2.4/include -L/libssh2-1.2.4/src/obj -L/openssl-0.9.8k/ -L/SecuritySDK/3.0.13/RC/LATEST/security/lib rhost.o rpipe.o rutils.o -o rpip -lssh2 -ldl -lnsl -lresolv -lhash -lhandlers -lcrypto -lssl -lz -lbpwp3.

The order of libraries and object files in the parameter list matters. Read about it here.

edited May 23 '17 at 12:18

Community

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answered Jan 06 '11 at 16:02

Raphael Bossek

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score 1 · Answer 2 · answered Jan 06 '11 at 13:54

1

If C works and C++ doesn't, then it sounds like you're failing to include the libssh2 function prototypes in an extern "C" {} block, as described here. (You should double-check the header file; I'm a bit surprised that it doesn't use extern "C" {} itself.)

answered Jan 06 '11 at 13:54

Josh Kelley

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@Avinash: Then I suspect that you're doing something wrong in your build. You'll need to provide more information about how you're building your code. – Josh Kelley Jan 06 '11 at 14:00
When I say C work, I tried the examples provided with libssh which are in C and they work with the same build command. – Avinash Jan 06 '11 at 14:07
@Avinash: Would you mind posting the exact build command that the example code uses? I wonder if you're somehow getting a different libssh2 (one provided by your Linux distro?) that doesn't define those functions... – Josh Kelley Jan 06 '11 at 14:38
I am not using libssh2 provided by linux distro. I am have build my own libssh2 – Avinash Jan 06 '11 at 14:39
@Avinash: Are you building libssh2 itself with the C or C++ compiler? – Ben Voigt Jan 06 '11 at 15:05

libssh2 and C++

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