Unable to find gmp's shared libraries using g++

[JamesBowen]

(note beforehand that if you know an easy-to-use bigint type library that you can give me step by step instruction on how to set up, you have done far more for me than solving this problem would. That'd be great. )

Here's what's happening:

I am trying to compile this C++ program:

	#include <iostream>
	#include <gmpxx.h>

	int Ackermann(int m, int n);
	
	using namespace std;

	int main(void)
	{
	mpz_class a;
	a = 1;
	a = a*a;	a = a*a;
	cout<< a;
	/*
	    int m = 4, n = 4;
	    cout <<"\n\nAckermann's function for (" << m << "," << n << ") is " << Ackermann(m,n);
	    return 0;*/
	}
	
	int Ackermann(int m, int n)
	{
		if (m == 0)
		{
			return (n+1);
		}
		else if (n == 0)
		{
			return (Ackermann(m-1,1));
		}
		else
		{
			return (Ackermann(m-1,Ackermann(m,n-1)));
		}
	}

However, when I compile it like this:

g++ ackermann.cpp -o ackermann -lgmpxx -lgmp

And then run it, I get this error:

./ackermann: error while loading shared libraries: libgmpxx.so.4: cannot open shared object file: No such file or directory

Now, it is fairly obvious that it can't find the shared libraries. I figured I'd see what I could do to fix it, and came across this rather interesting file: /home/james/gmp-4.2.4/libgmpxx.la

Here are the contents:

# libgmpxx.la - a libtool library file
# Generated by ltmain.sh - GNU libtool 1.5.24 (1.1220.2.455 2007/06/24 02:13:29)
#
# Please DO NOT delete this file!
# It is necessary for linking the library.

# The name that we can dlopen(3).
dlname='libgmpxx.so.4'

# Names of this library.
library_names='libgmpxx.so.4.0.4 libgmpxx.so.4 libgmpxx.so'

# The name of the static archive.
old_library='libgmpxx.a'

# Libraries that this one depends upon.
dependency_libs=' /home/james/gmp-4.2.4/libgmp.la'

# Version information for libgmpxx.
current=4
age=0
revision=4

# Is this an already installed library?
installed=no

# Should we warn about portability when linking against -modules?
shouldnotlink=no

# Files to dlopen/dlpreopen
dlopen=''
dlpreopen=''

# Directory that this library needs to be installed in:
libdir='/usr/local/lib'
relink_command="(cd /home/james/gmp-4.2.4; /bin/bash ./libtool --mode=relink g++ -m32 -O2 -fomit-frame-pointer -mtune=core2 -march=core2 -o libgmpxx.la -rpath /usr/local/lib -version-info 4:4:0 dummy.lo cxx/isfuns.lo cxx/ismpf.lo cxx/ismpq.lo cxx/ismpz.lo cxx/ismpznw.lo cxx/osdoprnti.lo cxx/osfuns.lo cxx/osmpf.lo cxx/osmpq.lo cxx/osmpz.lo libgmp.la @inst_prefix_dir@) "

It looks to me like if g++ could make use of the information in this file, it might be happy. I'm not entirely sure, however.

Now, I've done a fair bit of Linux and command-line related work, as well as C++ programming, but I haven't done much of the two together. Maybe it's as simple as setting an environment variable. Any help would be much appreciate, however, and I would think of you when I finish this assignment.

[dwhitney67]

The gmpxx header file is located in /usr/include. The libraries are in /usr/lib.

If you do not have these on your system, then perhaps you need to install the appropriate development package for these. If I knew the name of the package I would cheerfully provide it here, but unfortunately I do not know it.

[JamesBowen]

The gmpxx header file is located in /usr/include. The libraries are in /usr/lib.

If you do not have these on your system, then perhaps you need to install the appropriate development package for these. If I knew the name of the package I would cheerfully provide it here, but unfortunately I do not know it.

Wow, yeah, that actually fairly obvious reading the last 1/3 of the file or so. I can't believe I missed that.

UPDATE:
Yeah, that did the trick. Huge thanks, man!

[Abhishek4563]

I am having the same problem ... cannot really understand how did you fix it .. I checked my usr/lib and it is present there .. do i need to set PATH or LD_LIBRARY_PATH .. and if yes then how to ??

Thx

[dwhitney67]

I am having the same problem ... cannot really understand how did you fix it .. I checked my usr/lib and it is present there .. do i need to set PATH or LD_LIBRARY_PATH .. and if yes then how to ??

Thx

Could you please be more specific, wrt which library is in /usr/lib, and also please provide the gcc/g++ command that you are using to link your application?

Typically GCC is able to locate libraries in /usr/lib. You can verify this by running the following command and examining the output for the "libraries".

gcc -print-search-dirs

[Abhishek4563]

vindhya@Vindhya-desktop:~/DDP$ g++ trymain_p1.C -lgmpxx -lgmp
vindhya@Vindhya-desktop:~/DDP$ ./a.out
./a.out: error while loading shared libraries: libgmpxx.so.4: cannot open shared object file: No such file or directory
vindhya@Vindhya-desktop:~/DDP$ ls /usr/local/lib
libgmp.a   libgmp.so.3      libgmpxx.la    libgmpxx.so.4.1.0
libgmp.la  libgmp.so.3.5.0  libgmpxx.so    python2.6
libgmp.so  libgmpxx.a       libgmpxx.so.4
vindhya@Vindhya-desktop:~/DDP$ ls /usr/local/include
gmp.h  gmpxx.h
vindhya@Vindhya-desktop:~/DDP$ g++ -print-search-dirs
install: /usr/lib/gcc/x86_64-linux-gnu/4.3.3/
programs: =/usr/lib/gcc/x86_64-linux-gnu/4.3.3/:/usr/lib/gcc/x86_64-linux-gnu/4.3.3/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.3.3/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/libexec/gcc/x86_64-linux-gnu/4.3.3/:/usr/libexec/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.3.3/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.3.3/../../../../x86_64-linux-gnu/bin/x86_64-linux-gnu/4.3.3/:/usr/lib/gcc/x86_64-linux-gnu/4.3.3/../../../../x86_64-linux-gnu/bin/
libraries: =/usr/lib/gcc/x86_64-linux-gnu/4.3.3/:/usr/lib/gcc/x86_64-linux-gnu/4.3.3/:/usr/lib/gcc/x86_64-linux-gnu/4.3.3/../../../../x86_64-linux-gnu/lib/x86_64-linux-gnu/4.3.3/:/usr/lib/gcc/x86_64-linux-gnu/4.3.3/../../../../x86_64-linux-gnu/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/4.3.3/../../../x86_64-linux-gnu/4.3.3/:/usr/lib/gcc/x86_64-linux-gnu/4.3.3/../../../../lib/:/lib/x86_64-linux-gnu/4.3.3/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/4.3.3/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/4.3.3/../../../../x86_64-linux-gnu/lib/:/usr/lib/gcc/x86_64-linux-gnu/4.3.3/../../../:/lib/:/usr/lib/

in the above I 1. compiled the program.. no prob 2. Ran it ...prob 3. contents of usr/local/lib and usr/local/include 4. output of the command you asked

Thanx

[johnl]

Hi,

My suspicion is that you need to tell the runtime linker where it can find libgmpxx.so.4.

I would give this a shot:

vindhya@Vindhya-desktop:~/DDP$ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib

vindhya@Vindhya-desktop:~/DDP$ ./a.out

[Abhishek4563]

I think it worked ..not really sure though ..I am getting floating point exception ..may be something in the code is doing it.. by the way is the LD_LIbrary_pah permanently changed or I will have to change it every time i start the computer?
Thanx a lot

[dwhitney67]

The suggestion provided by johnl should work.

An alternative is to augment your ldconfig search paths by inserting a new file in /etc/ld.so.conf.d (or something similar).

Create a file (you must have root privileges) within this directory, and within it place the following statement:

/usr/local/lib

After saving the file, run "ldconfig".

sudo ldconfig

If all goes well, you should not need to specify the LD_LIBRARY_PATH again.

[johnl]

I think it worked ..not really sure though ..I am getting floating point exception ..may be something in the code is doing it.. by the way is the LD_LIbrary_pah permanently changed or I will have to change it every time i start the computer?
Thanx a lot

Sounds to me like it worked. I would debug your code to find where the FPE is coming from

Follow dwhitney67's post to make the LD_LIBRARY_PATH change permanent.