I'm trying to include the MQTT-C-Client-Library in a simple C++ project.
I have included the header file succesfully like this #include "MQTTClient.h". Compiling it in the linux terminal was printing this errors:
[xy#localhost mosquittoProject]$ sudo g++ *.cpp -o MQTTTest
/tmp/ccHn3s6m.o: In function `main':
mosquitto_test.cpp:(.text+0x11e): undefined reference to `MQTTClient_create'
mosquitto_test.cpp:(.text+0x13f): undefined reference to `MQTTClient_connect'
collect2: error: ld returned 1 exit status
I figured out that I need to link the library after some googling: Example MQTT Client Code not working C
Based on this question and answer I tried compiling it again like this:
sudo g++ -L/home/xy/Desktop/paho.mqtt.c/build/output/ *.cpp -l paho-mqtt3c -o MQTTTest
Which compiles fine but when running I get still an error.
Console commands and output:
[xy#localhost mosquittoProject]$ sudo g++ -L/home/xy/Desktop/paho.mqtt.c/build/output/ *.cpp -l paho-mqtt3c -o MQTTTest
[xy#localhost mosquittoProject]$ ./MQTTTest
./MQTTTest: error while loading shared libraries: libpaho-mqtt3c.so.1: cannot open shared object file: No such file or directory
I replaced the actual username by xy in this post.
What am I doing wrong here?
The problem looks like the library (libpaho-mqtt3c.so.1) is not on the library path.
It looks like you are linking against the build location of the library and have not installed it to the default system location (e.g. /usr/local/lib) by running sudo make install.
By default on Linux the runtime linker searches the locations listed in /etc/ld.so.conf and /etc/ld.so.conf.d. if you edit these remember to run sudo ldconfig to update the cache.
You can add the location of the library to the LD_LIBRARY_PATH environment variable e.g.:
$ LD_LIBRARY_PATH=/home/xy/Desktop/paho.mqtt.c/build/output/ ./MQTTTest
Related
I'm trying to generate a mex function usigin external libraries. I'm using Ubuntu 18 and Matlab R2021a.
In particular I want to compile my file.cpp that uses my cpp library called model.
What I did is
mex -I<path_library_include> -L<path_library_so_file> -lmodel.so -lboost_system -lstdc++ file.cpp -v
where in -I i put the path where is the include of the library in -L the path in which the libmodel.so is located, then I added 2 more libraries and at the end the source file that I want to compile.
In this way I can compile my source but when I try to execute the mex function I get:
libmodel.so: cannot open shared object file: No such file or directory
I also tested the library outside matlab and works fine, this is the command that I use to compile the library outside Matlab
gcc -Wall -I<path_library_include> -L<path_library_so_file> main.cpp -lmodel -lboost_system -lstdc++ -o main
What could be the problem with Matlab?
Thanks to 273K that gave me the right direction.
The problem was that the LD_LIBRARY_PATH was not configured well in fact running /sbin/ldconfig -v my library was not present. So to add the shared library i created a new file as root in /etc/ld.so.conf.d/ called mylib.conf it is not important the name just the extension. Then I run
sudo ldconfig
after that the library was present in fact running
/sbin/ldconfig -v | grep model
where model is the name of my library. it is possible to see the output.
I'm trying to test out a new dev environment and I am having some problems referencing some of the required Qt libraries.
First I ran this:
$ g++ HelloWorld.C -o HelloWorld -I /usr/local/Trolltech/Qt-4.5.1/include/QtCore/ -I /usr/local/Trolltech/Qt-4.5.1/include/
and got this error:
/tmp/ccmsm4kZ.o: In function `QString::QString(char const*)':
HelloWorld.C:(.text._ZN7QStringC2EPKc[_ZN7QStringC5EPKc]+0x1d): undefined reference to `QString::fromAscii_helper(char const*, int)'
/tmp/ccmsm4kZ.o: In function `QString::~QString()':
HelloWorld.C:(.text._ZN7QStringD2Ev[_ZN7QStringD5Ev]+0x2d): undefined reference to `QString::free(QString::Data*)'
collect2: ld returned 1 exit status
So then I added reference to the QtCore library via:
$ g++ HelloWorld.C -o HelloWorld -I /usr/local/Trolltech/Qt-4.5.1/include/QtCore/ -I /usr/local/Trolltech/Qt-4.5.1/include/ -L /usr/local/Trolltech/Qt-4.5.1/lib -lQtCore
which removed the compile errors, however when I try to run the program I get this error:
./HelloWorld: error while loading shared libraries: libQtCore.so.4: cannot open shared object file: No such file or directory
I wasn't able to find a solution for this problem via google. Anyone have advice?
That error indicates that while the linker can find the library at compilation, it can't find it during runtime.
You should update your LD_LIBRARY_PATH to include that location like this:
In ~.bashrc probably somewhere near the bottom:
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/Trolltech/Qt-4.5.1/lib
Alternatively, if you want to make this persistent throughout your system (and have root access), you can make an entry in /etc/ld.so.conf.d (on RedHat, I'm not sure about the other distributions)
touch /etc/ld.so.conf.d/qt.conf
Add the path to this file, and then update your runtime via /sbin/ldconfig
I need to use libcurl in a piece of software I am writing on my ubuntu machine. I am using Eclipse to write and compile all of the software. When I put the libcurl files in the same folder as the .cpp file, and include the curl.h file in the header, When I attempt to compile the program, It comes up with these errors:
Building target: sms
Invoking: GCC C++ Linker
g++ -o"sms" ./src/sms.o
./src/sms.o: In function `main':
/home/geekman/workspace/sms/Debug/../src/sms.cpp:38: undefined reference to `curl_easy_init'
/home/geekman/workspace/sms/Debug/../src/sms.cpp:42: undefined reference to `curl_easy_setopt'
/home/geekman/workspace/sms/Debug/../src/sms.cpp:44: undefined reference to `curl_easy_setopt'
/home/geekman/workspace/sms/Debug/../src/sms.cpp:46: undefined reference to `curl_easy_perform'
/home/geekman/workspace/sms/Debug/../src/sms.cpp:47: undefined reference to `curl_easy_cleanup'
collect2: ld returned 1 exit status
make: *** [sms] Error 1
I took the contents of the include folder from libcurl, and placed them in the same folder as the .cpp file. then in the header of the .cpp file, I typed:
#include <curl/curl.h>
I also tried:
#include "curl/curl.h"
Any ideas on the problem? Thanks.
Your header file inclusions are just fine; your problem is occurring at the linking step. In order to link against libcurl, you need to add the -lcurl command line option, assuming it's installed in a standard directory:
g++ -o sms ./src/sms.o -lcurl
If it's not installed in a standard directory, you also need to add the -L/path/to/libcurl, e.g. something like:
# Assuming that /home/geekman/workspace/libcurl is where libcurl.a is located
g++ -o sms ./src/sms.o -L/home/geekman/workspace/libcurl -lcurl
Also note that the -lcurl option has to appear after the list of object files you're linking, otherwise it won't link properly.
You can try to use curl-config --libs.
An alternate answer (the first one is excellent). Consider using the output returned by "pkg-config --libs libcurl" as an argument to your compiler.
For example,
CPPFLAGS=`pkg-config --libs libcurl`
g++ $CPPFLAGS myfile.o
Pkg-config is a standard way for open source libraries to communicate to you how to link against them / #include their files.
Anyone who is using ecplise CDT then you need to do following. First on terminal enter
curl-config --libs
On my machine, the result is
-L/usr/lib/i386-linux-gnu -lcurl
then do according to this screenshot and you will be able to compile. btw don't forget to add header files in your code
So you enter library folder path without -L and library name without -l because they will be automatically added by linker.
You have to link the library to your program. With gcc (and most other compilers) you can specify the libraries to link with -lname_wo_lib, e.g. -lcurl
Also see GNU GCC Manual - Options for Linking for a detailed explanation of the options Adam Rosenfield said. For standard search directories, see An Introduction to GCC - for the GNU Compilers gcc and g++ - Setting Search Paths.
In addition to the first answer, I had to link the curlpp library too. So to compile the main.cpp file which included the curlpp I had to do:
g++ main.cpp -lcurl -lcurlpp
Using only one of the two links would return different errors regarding different links. It is important to remind that this only worked because I had installed all the necessary libraries in the standard include folders
I am have been attempting to get a C++ project setup using boost file system library using eclipse. I followed these directions to install boost on my system. The directions where pretty much
download
extract
run bootstrap.sh
run ./bjam architecture=combined
That seemed to go fine, no errors. I then fired up eclipse and created a new test project called test with a single file called test.cpp. The code in it is:
#include <stdio.h>
#include <boost/filesystem.hpp>
int main() {
boost::filesystem::path path("/Users/schoen"); // random pathname
bool result = boost::filesystem::is_directory(path);
printf("Path is a directory : %d\n", result);
return 0;
}
This is just something simple to make sure it is all set up correctly. Of course I tried to compile at this point and it failed. Did some googling and found this site. It said to add the boost library to the linker by going to project properties and adding "boost_filesystem". I tried this, and well it didn't work.
Can someone point me in the right direction or give me a hint to how to set up Boost in an Eclipse project?
I am new to C++ and Eclipse, and most my experience is in Java with Netbeans. So I am pretty lost at the moment.
UPDATE
I just wanted to update on what I have tried based on the answers given.
Based on Alex's suggestion I added boost_system and boost_filesystem to the linker list. I was still getting the same compiler errors.
Following the suggestion from rve I added the path to the boost libraries to the Library search path. When this did not work. I cleared out the linker list and tried it with just the library search path. This also did not work.
I then cleared the Library search path. I then manually edited the command on the linker window to be 'g++ -L/Users/jacobschoen/Library/boost_1_45_0/stage/lib -lboost -lboost_filesystem'. This also did not work.
In all of these I tried setting the path to boost to be '/Users/jacobschoen/Library/boost_1_45_0' and '/Users/jacobschoen/Library/boost_1_45_0/stage/lib'. Neither worked.
As requested the comiler error for the above code is:
**** Build of configuration Debug for project test ****
make all
Building file: ../src/test.cpp
Invoking: GCC C++ Compiler
g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/test.d" -MT"src/test.d" -o"src/test.o" "../src/test.cpp"
../src/test.cpp:10:32: warning: boost/filesystem.hpp: No such file or directory
../src/test.cpp: In function 'int main()':
../src/test.cpp:13: error: 'boost' has not been declared
../src/test.cpp:13: error: expected `;' before 'path'
../src/test.cpp:14: error: 'boost' has not been declared
../src/test.cpp:14: error: 'path' was not declared in this scope
make: *** [src/test.o] Error 1
If any one has any further suggestions I am still trying.
Second Update
On a suggestion by rholmes I added an include library along with the linker list and library search path. So now the compile error is:
**** Build of configuration Debug for project test ****
make all
Building target: test
Invoking: MacOS X C++ Linker
g++ -L/Users/jacobschoen/Library/boost_1_45_0 -o "test" ./src/test.o -lboost_system -lboost_filesystem
ld: library not found for -lboost_system
collect2: ld returned 1 exit status
make: *** [test] Error 1
Any ideas?
Just wanted to be clear on what actually worked, since it was kinda pieced together from a few answers.
Download the boost files and extract them to where you want to put them.
In your terminal navigate to the directory and run ./bootstrap.sh
When that is done run ./bjam (this takes a while so go smoke and get a cup of coffee)
Open up your eclipse Project and go to Project > Properties > C/C++ Build > Settings
Click on MacOS X C++ Linker > Libraries.
You should see a split window with the top being for 'Libraries (-l)'. In this section add both boost_system and boost_filesystem. In the bottom section it should be for 'Library Search Path (-L)'. Here you want to put the path to the stage/lib directory inside where you extracted the boost download. It should look similar to below:
Click GCC C++ Compiler > Includes. This will be a single pane where it says 'Include Paths (-I)', well I think it is an I as he font is weird and could be a lower case l also. Anyway in that section add the path to where you put boost without the stage/lib part. It should look like below:
Everything should compile now with out a problem, and if you need to use any other boost libraries it should be just a matter of adding it to the linker section where boost_filesystem and boost_system are. Enjoy.
Not sure where you do this in Eclipse these days, but under the include paths for Eclipse should be the path to the main boost directory (/Users/jacobschoen/Library/boost_1_45_0?). The compiler line should have something like the following in it, I would think:
Invoking: GCC C++ Compiler
g++ -I/Users/jacobschoen/Library/boost_1_45_0 -O0 -g3 -Wall -c -fmessage-length=0 -MMD (etc..)
Update: Looking at my system, the linker path on yours might be more appropriately:
-I/Users/jacobschoen/Library/boost_1_45_0/stage/lib
Depending, of course, upon how you've installed and built boost -- this is with my most recent attempt with a full source build. Depending upon how you obtained boost, this may or may not be different. I recently redid the boost on my Mac for 64 bit and haven't had much time to try it yet....
Add boost_system to the linker list, together with boost_filesystem.
I had recently uninstalled the boost rpm and installed Boost like how you did. I had no problems running Boost programs in Eclipse. I didn't add any extra parameters. Just installed boost and ran Boost programs. It works fine.
Tried your program in the vi editor. Commented out everything in main
#include <cstdio>
#include <boost/filesystem.hpp>
int main() {
/*boost::filesystem::path path("/Users/schoen"); // random pathname
bool result = boost::filesystem::is_directory(path);
printf("Path is a directory : %d\n", result);*/
return 0;
}
and it still gave this error:
/tmp/cc7TAIYS.o: In function `__static_initialization_and_destruction_0(int, int)':
test.cpp:(.text+0x29): undefined reference to `boost::system::get_system_category()'
test.cpp:(.text+0x35): undefined reference to `boost::system::get_generic_category()'
test.cpp:(.text+0x41): undefined reference to `boost::system::get_generic_category()'
test.cpp:(.text+0x4d): undefined reference to `boost::system::get_generic_category()'
test.cpp:(.text+0x59): undefined reference to `boost::system::get_system_category()'
collect2: ld returned 1 exit status
I'm puzzled. Boost programs work on my system, but your program's header files itself are giving a problem. I doubt it's a problem with Eclipse. It has to be something else.
I just ran into something very similar to this using eclipse and CDT... It turns out, using ubuntu and apt-get, libboost_system installs as libboost_system.1.40.0 in /usr/lib
If you try to add it via the library tab in Helios it will complain because it is looking for *.so and *.s0.1.40.0 clearly doesn't match that. However after looking closely at what the linker was trying to doo, I just typed the raw string "boost_system" into the include path adder. This resulted in the linker doing a " -lboost_system" which is a format the linker knows how to deal with in resolving version dependency... If you instead put in the full path to the .so file, the linker will just complain because it tries to do a " -l/usr/lib/libboost_system.so.1.40.0" .
So take my advice and just type in the simple " boost_system" after doing an apt-get install.. It will make it all very easy.
The packages I'm toying with here are rather unknown, but nevertheless the problem is rather generic. Basically, I'm trying to compile Python module (called rql) with C++ extension. The extension uses external framework called gecode, which contains several libraries. I compiled gecode and installed locally. Now, let the output speak for itself:
red#devel:~/build/rql-0.23.3$ echo $LD_LIBRARY_PATH
/home/red/usr/lib
red#devel:~/build/rql-0.23.3$ ls $LD_LIBRARY_PATH | grep libgecodeint
libgecodeint.so
libgecodeint.so.22
libgecodeint.so.22.0
red#devel:~/build/rql-0.23.3$ python setup.py build
running build
running build.py
package init file './test/__init__.py' not found (or not a regular file)
running build_ext
building 'rql_solve' extension
g++ -pthread -shared build/temp.linux-i686-2.5/gecode-solver.o -lgecodeint -lgecodekernel -lgecodesearch -o build/lib.linux-i686-2.5/rql_solve.so
/usr/bin/ld: cannot find -lgecodeint
collect2: ld returned 1 exit status
error: command 'g++' failed with exit status 1
LD_LIBRARY_PATH is for runtime linker/loader (same effect could be achieved with ldconfig ). What you need is the -L flag:
-L/home/red/usr/lib
on the compiler command line.
Edit:
And - thanks to #bjg for reminding me - you can use LIBRARY_PATH if you don't want to mess with compiler options.
You've apparently modified LD_LIBRARY_PATH to point to a non-standard location in your home directory. Do you know if LD_LIBRARY_PATH in the environment used to call g++ in setup.py matches your shell's environment?
See if you can pass arguments to setup.py to modify the library path or simply pass -L/home/red/usr/lib to g++.