Linking problem with jpeg and the stdc++ (linux 64bits)

tandu · #1 08-Apr-2009, 09:30

Hello,
This is my first post. My name is Giuseppe, I’m a programmer and work in image processing for satellite application.
I have a problem to compile a c++ code using jpeg lib on a 64 bits Linux machine (fedora 9 64bits).

To explain better the problem, I have the follows two simple program (in c and in c++)

CPP / C++ / C Code:

/*
*  jpegtest.c
*/ 

#include <stdio.h>
#include <jpeglib.h>

int main(int argc, char *argv[])
{
        struct jpeg_compress_struct cinfo;
        jpeg_create_compress(&cinfo);

        printf("hello world\n");
}

and

CPP / C++ / C Code:

/*
*  jpegtest.cpp
*/ 
#include <iostream>
#include <jpeglib.h>

using namespace std;

int main(int argc, char *argv[])
{
        struct jpeg_compress_struct cinfo;
        jpeg_create_compress(&cinfo);

        cout << "hello world" << endl;
}

If I try to compile, I obtain the follow situation:

gcc jpegtest.c -o jpegtest_c -ljpeg
OK
g++ jpegtest.cpp -o jpegtest_cpp –ljpeg
undefined reference to `jpeg_CreateCompress(jpeg_compress_struct*, int, unsigned long)'

gcc jpegtest.cpp -o jpegtest_cc -ljpeg -lstdc++
undefined reference to `jpeg_CreateCompress(jpeg_compress_struct*, int, unsigned long)'

I reach to compile c code that use jpeg lib but not c++ code!

its seams that the stdc++ make some confusion in the linking phase. I have already compiled that code on a 32bits linux machine without problems.

Someone can help me? Many thanks!

Giuseppe

davekw7x · #2 08-Apr-2009, 10:14

Quote:

Originally Posted by tandu

Code:

g++ jpegtest.cpp -o jpegtest_cpp –ljpeg
undefined reference to `jpeg_CreateCompress(jpeg_compress_struct*, int, unsigned long)'

What happens when you try

Code:

g++ jpegtest.cpp -o jpegtest_cpp -ljpeg

Note that my command line has an ascii '-' in front of the "ljpeg." Yours has something else. (Hex e2 80 93) Maybe your compiler is set up differently than on my installation, and I have no way of testing unicode or whatever other input encoding you (and your Fedora installation) are using. Note also, that my compiler gives a "no such file or directory message rather than the undefined symbol one, so I'm guessing that is not hte problem. Just a guess.

However...

The command line that I showed works on my Centos 5.2 64-bit workstation (g++ version 4.1.2). I have no way of testing Fedora 64-bit distributions these days, but I have noted in the past that sometimes some distributions (not just Fedora) don't set up library search paths correctly in cases where 32-bit and 64-bit libraries are both installed. So, if there is libjpeg.so in /usr/lib and also in /usr/lib64, the linker might erroneously pick the 32-bit library (in /usr/lib), in which case you could get an "undefined reference" error.

Quote:

Originally Posted by tandu

Code:

gcc jpegtest.cpp  -o jpegtest_cc -ljpeg -lstdc++
undefined reference to `jpeg_CreateCompress(jpeg_compress_struct*, int, unsigned long)'

I'm not sure why you would want to do this, but I'm thinking that if the "g++" command line doesn't work, then "gcc...-lstdc++" won't work either.

Quote:

Originally Posted by tandu

its seams that the stdc++ make some confusion in the linking phase. I have already compiled that code on a 32bits linux machine without problems.

If my command line doesn't work, then try the following:

Look for libjpeg files in /usr/lib and /usr/lib64:

Code:

cd /usr/lib
ll -d *jpeg*
cd /usr/lib64
ll -d *jpeg*

If libjpeg.so appears in both directories, then you might try the following:

Code:

 g++  jpegtest.cpp -L/usr/lib64 -ljpeg -ojpegtest_cpp

If this works, then you might even temporarily change the name of "/usr/lib/libjpeg.so" to something else. See Footnote.
Try compiling again with

Code:

 g++  jpegtest.cpp -ljpeg -ojpegtest_cpp

Regards,

Dave

Footnote:

The "correct" thing to do, instead of renaming the library file of an installed 32-bit package is to use yum to uninstall the 32-bit package. I can't imagine that you would need the 32-bit library on a 64-bit installation anyhow. The "rename" trick is just for verification.

tandu · #3 08-Apr-2009, 10:51

Hello Dave,
Thanks a lot for the answer!

Now in the machine exists only the jpeg lib installed from the source distribution jpeg-6b.tar.gz, libjpeg appears only in the directory /usr/local/lib (checked with ldconfig -v).
I have changed the order of the argument in the command line (as you suggest) but the result is the same.

It’s very strange problem, I don’t understand why the compilation ends successful when compile c code end fails with c++ code ….. maybe this is a sign to change work?!

davekw7x · #4 08-Apr-2009, 11:31

Quote:

Originally Posted by tandu

...installed from the source distribution jpeg-6b.tar.gz, libjpeg appears only in the directory /usr/local/lib (checked with ldconfig -v)

.
How did you install the library? Did you compile it from scratch or what? I always use yum for such things so that all file locations are known and so that upgrades can happen in a sane way.

The fact that you didn't get a messag about not finding the file indicates that it found a libjpeg file somewhere. See Footnote.

Try

Code:

yum info "*libjpeg*"

You might try uninstalling the jpeg stuff that you compiled from scratch and, then:

As root:

Code:

yum install libjpeg libjpeg-devel

This works with RedHat-like distributions like Centos, and I assume that it would work with Fedora.

Sorry that I can't help beyond this point.

Regards,

Dave

Footnote:

In your source installation does /usr/include/jpeglib.h have the following near the beginning:

CPP / C++ / C Code:

#ifdef __cplusplus
extern "C" {
#endif

And the following near the end:

CPP / C++ / C Code:

#ifdef __cplusplus
}
#endif

If not, then including this header in a c++ program won't work. You could get the undefined symbol error message.

davekw7x · #5 08-Apr-2009, 15:26

Quote:

Originally Posted by davekw7x

...
In your source installation does /usr/include/jpeglib.h have the following near the beginning:

CPP / C++ / C Code:

#ifdef __cplusplus
extern "C" {
#endif

And the following near the end:

CPP / C++ / C Code:

#ifdef __cplusplus
}
#endif

...

I just downloaded and untarred jpegsrc.v6b.tar.gz.

Indeed, the cplusplus stuff was not in jpeglib.h.

Here's a plan: Copy jpeglib.h to a file with another name (just in case). For example:

Code:

cp jpeglib.h jpeglib_distribution.h

Then edit jpeglib.h to insert the lines shown above something like this:

Change stuff at the beginning (somewhere around line 13) to:

CPP / C++ / C Code:

#ifndef JPEGLIB_H
#define JPEGLIB_H

#ifdef __cplusplus
extern "C" {
#endif

/*
 * First we include the configuration files that record how this
 * installation of the JPEG library is set up.  jconfig.h can be
.
.
.

And near the end:

CPP / C++ / C Code:

#ifdef JPEG_INTERNALS
#include "jpegint.h"		/* fetch private declarations */
#include "jerror.h"		/* fetch error codes too */
#endif

#ifdef __cplusplus
}
#endif

#endif /* JPEGLIB_H */