boost lib error in netbeans - c++

Question

i stripped all classes from project, which left three errors like this:
error_code.hpp:222: undefined reference to `boost::system::generic_category()
using Netbeans IDE
clicked on file -> Project Properties -> Linker
next to Libraries, added libboost_system.so
which got rid of the three undefined reference to boost::system::generic_category()
now it gives:
CLEAN SUCCESSFUL (total time: 123ms)
cd '/home/michaeleric/NetBeansProjects/NNW'
/usr/bin/make -f Makefile CONF=Debug
"/usr/bin/make" -f nbproject/Makefile-Debug.mk QMAKE= SUBPROJECTS= .build-conf
make[1]: Entering directory `/home/michaeleric/NetBeansProjects/NNW'
"/usr/bin/make" -f nbproject/Makefile-Debug.mk dist/Debug/GNU-Linux/nnw
make[2]: Entering directory `/home/michaeleric/NetBeansProjects/NNW'
mkdir -p build/Debug/GNU-Linux/_ext/d028d44d
rm -f "build/Debug/GNU-Linux/_ext/d028d44d/CGrid.o.d"
g++ -c -g -MMD -MP -MF "build/Debug/GNU-Linux/_ext/d028d44d/CGrid.o.d" -o build/Debug/GNU-Linux/_ext/d028d44d/CGrid.o ../../Desktop/NN_22_05_17/CGrid.cpp
mkdir -p dist/Debug/GNU-Linux
g++ -o dist/Debug/GNU-Linux/nnw build/Debug/GNU-Linux/_ext/d028d44d/CGrid.o -L/usr/include/boost -lboost_system
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o: In function `_start':
collect2: error: ld returned 1 exit status
make[2]: *** [dist/Debug/GNU-Linux/nnw] Error 1
make[2]: Leaving directory `/home/michaeleric/NetBeansProjects/NNW'
make[1]: *** [.build-conf] Error 2
make[1]: Leaving directory `/home/michaeleric/NetBeansProjects/NNW'
make: *** [.build-impl] Error 2
BUILD FAILED (exit value 2, total time: 6s)
what does this error mean and how to fix?
class that rest requires
#include </usr/include/boost/thread/thread.hpp>
#include </usr/include/boost/thread/xtime.hpp>
#include </usr/include/boost/iostreams/write.hpp>
#define byte unsigned char
#define Thread boost::thread
class CGrid
{
Thread* GetThread();
bool SetThread(Thread* thread);
};

Answer 1

If I compile this with
g++ test.cpp -lboost_system
I get the same linker error which is
/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
However, if I add an empty main function, it compiles fine. (I also replaced your ugly #define replacements with typedef.)
#include </usr/include/boost/thread/thread.hpp>
#include </usr/include/boost/thread/xtime.hpp>
#include </usr/include/boost/iostreams/write.hpp>
typedef unsigned char byte;
typedef boost::thread Thread;
class CGrid
{
Thread* GetThread();
bool SetThread(Thread* thread);
};
int main() {}
If this is meant to be an object file and main is in another translation unit, compile it as such with the -c parameter:
g++ -c test.cpp -lboost_system