Linking programs to C++ Project in Eclipse? Linux - c++

Question

I am given the command to link programs:
g++ -o prog_name prog_name.cc -lsicklms-x -pthread
However, I'm not using the command line, I'm using eclipse.
My Project is called "Test" and I have only 1 class "main.cpp" that is this:
/*
* Test.cpp
*
* Created on: Dec 1, 2011
* Author: igvc
*/
#include <iostream>
#include <sicklms-1.0/SickLMS.hh>
using namespace std;
using namespace SickToolbox;
int main(int argc, char *argv[]) {
/* Specify device path and baud */
string dev_path = "/dev/ttyUSB0";
sick_lms_baud_t lms_baud = SickLMS::SICK_BAUD_38400;
/* Define buffers for return values */
unsigned int measurements[SickLMS::SICK_MAX_NUM_MEASUREMENTS] = {0};
unsigned int num_measurements = 0;
/* Instantiate the object */
SickLMS sick_lms(dev_path);
try {
/* Initialize the device */
sick_lms.Initialize(lms_baud);
/* Grab some measurements */
for(unsigned int i = 0; i < 10; i++) {
sick_lms.GetSickScan(measurements,num_measurements);
cout << "\t" << num_measurements << endl;
}
/* Uninitialize the device */
sick_lms.Uninitialize();
}
catch(...) {
cerr << "error" << endl;
return -1;
}
return 0;
}
I'm getting all these errors:
undefined reference to `SickToolbox::SickLMS::~SickLMS()`
undefined reference to `SickToolbox::SickLMS::GetSickScan(unsigned int*, unsigned int&, unsigned int*, unsigned int*, unsigned int*, unsigned int*, unsigned int*)'
undefined reference to `SickToolbox::SickLMS::Initialize(SickToolbox::SickLMS::sick_lms_baud_t)'
undefined reference to `SickToolbox::SickLMS::SickLMS(std::basic_string<char, std::char_traits<char>, std::allocator<char> >)'
undefined reference to `SickToolbox::SickLMS::Uninitialize()'
So I think it's a linking problem. And I have that above command to link, which the tutorial says is required, but I'm not sure how to set it up in eclipse.
Where the code says #include sicklms-1.0/SickLMS.hh, I did go to Project>Properties>C/C++ Build>Settings>GCC C++ Compiler>Directories and added the directory to the .h file and that resolved that problem, but now I'm getting those errors. I went to GCC C++ Linker>Libraries>Library search path(-L) and added the sicktoolbox-1.0.1 directory, but i don't know what to put in the Libraries(-l) part.
Thanks for any help, I'm really stuck on this.

Answer 1

Presumably you are using Eclipse CDT?
Right-click on your project and select Properties from the context menu.
In the Properties dialog, select C/C++ Build->Settings->GCC C++ Linker->Libraries
In the Libraries box, click on the + button to add a new library, type sicklms
Your library must be in the linker's path. /usr/lib and /usr/local/lib are fairly standard. The library name must be libsicklms.a or libsicklms.so for -l as the linker prepends lib to the library name.
If sicklms was installed from source with ./configure && make && make install then the library should be in the standard library path i.e. either /usr/lib or /usr/local/lib otherwise, your problem is not your linker, but the way sicklms was installed.
If any of the above instructions are not doable, you need to let me know
a) Version of Eclipse (Galileo, Indigo, etc)
b) If you have CDT installed.
c) How sicklms was installed on your system (package manager, built from source, etc).

Answer 2

Based entirely on what you've written here, I think in the -l part you need to just add -lpthread -lsicklms-x. But that's assuming Eclipse provides enough smarts to replace a tool such as make(1), which is really fantastic for rebuilding large projects.
Try creating a Makefile in your project directory like this:
LDFLAGS=-L/path/to/sicklms-directory -lsicklms-x -lpthread
Running make then gives:
$ make main
g++ -L/path/to/sicklms-directory -lsicklms-x -lpthread main.cpp -o main
/usr/bin/ld.bfd.real: cannot find -lsicklms-x
collect2: ld returned 1 exit status
make: *** [main] Error 1
(It fails because I don't have your libraries available. But it does show the command line that was executed to try to build the source.)
You can probably make some easy changes for compiling Java programs too. I've only got super-simplistic Java sources easily available, but the following Makefile lets me re-build them very easily:
$ cat Makefile
.SUFFIXES: .java .class
.java.class:
javac $<
all: Echo.class Test.class Compress.class
$ make Echo.class Test.class
javac Echo.java
make: `Test.class' is up to date.
$ rm *class
$ make
javac Echo.java
javac Test.java
javac Compress.java
(Note that the indented line is indented with a tab. It must be a tab. make(1) is mighty archaic in some seriously inconvenient ways.)