Compiling with POCO on C++: /usr/bin/ld cannot find -lPocoFoundationd

GATTACA · 01-01-2013, 08:26 AM

Hi.
Newbie question here so I apologize if this is a silly question.

I'm trying to use the Runnable and Threadpool libriares in POCO in my C++ project.
I'm working on CentOS 6.3 (64-bit) using g++ version 4.4.6 20120305 (Red Hat 4.4.6-4)

I've written my code based upon the online examples (correctly I think).

My problem is when compiling.
I get the following error: /usr/bin/ld: cannot find -lPocoFoundationd

This seems strange to me since the compile command specifies the correct path to the libraries and header files.

I installed the POCO project locally (I don't have root access to our server).
Here is how installed POCO:

Code:

cd $HOME/workspace/xProject
tar xzf poco-1.4.5.tar.gz
cd poco-*
./configure --prefix=$HOME/workspace/xProject/poco.lib
make
make install

The libraries are there now in $HOME/workspace/xProject/poco.lib (which is one directory up from the project's source code folder):

Code:

ls ../poco.lib/lib/*.so

../poco.lib/lib/libPocoFoundationd.so
../poco.lib/lib/libPocoFoundation.so
../poco.lib/lib/libPocoNetd.so
../poco.lib/lib/libPocoNet.so
../poco.lib/lib/libPocoUtild.so
../poco.lib/lib/libPocoUtil.so
../poco.lib/lib/libPocoXMLd.so
../poco.lib/lib/libPocoXML.so

Here are the commands I issued to compile the program (through a Makefile):

Code:

g++ -O2 -Wall -static -I../poco.lib/include -L../poco.lib/lib -lPocoFoundationd -lPocoFoundation -c xClass.cpp
g++ -O2 -Wall -static -I../poco.lib/include -L../poco.lib/lib -lPocoFoundationd -lPocoFoundation -c main.cpp
g++ -O2 -Wall -static -I../poco.lib/include -L../poco.lib/lib -lPocoFoundationd -lPocoFoundation -c globals.cpp
g++ -O2 -Wall -static -I../poco.lib/include -L../poco.lib/lib -lPocoFoundationd -lPocoFoundation -o finalApp.exe  xClass.o main.o globals.o

And then I get this error:

Code:

g++ -O2 -Wall -static -I../poco.lib/include -L../poco.lib/lib -lPocoFoundationd -lPocoFoundation -o  finalApp.exe  xClass.o main.o globals.o
/usr/bin/ld: cannot find -lPocoFoundationd
collect2: ld returned 1 exit status
make: *** [finalApp.exe] Error 1

Any suggestions what I'm doing wrong?

Thanks in advance for any and all help.
Happy New Year.

a4z · 01-01-2013, 08:59 AM

this
-lPocoFoundationd -lPocoFoundation

looks like you are linking against 2 times the same library
where one of them (with d postifx) is the debug version and the other one the release version
thats not a good idea, decide for one

you my also research the -static flag that you send to gcc
(On systems that support dynamic linking, this prevents linking with the shared libraries. On other systems, this option has no effect.)

*.so are dynamic libraries

GATTACA · 01-01-2013, 09:33 AM

Thanks for the quick reply!

I removed the -lPocoFoundationd library to no effect.
I still get the same error:

Code:

/usr/bin/ld: cannot find -lPocoFoundation

You were right about the -static flag though.
Removing the -static flag results in successful compilation, but not an executable program. Here is the error I get now:

Code:

$ ./finalApp.exe

./finalApp.exe: error while loading shared libraries: libPocoFoundation.so.15: cannot open shared object file: No such file or directory

I'm thinking I have to build the POCO library to produce static libraries instead of dynamic ones.

Any suggestions?
Their documentation on this point is difficult to find (at least for me).

a4z · 01-01-2013, 09:50 AM

you have an executable program
when you execute your binary, the system needs to know where to find the required libraries

if you have libraries in non default locations, like your poco libs, you need to inform you environment about additional directories where to look at

export LD_LIBRARY_PATH=/path/to/poco/libs
./theapp

then the system will look also in the locations specified in the LD_LIBRARY_PATH variable for required libraries

search for LD_LIBRARY_PATH for more information about that topic