question about boost asio

Question

i have following code

#include <boost/date_time/posix_time/posix_time.hpp>

#include <iostream>
#include <boost/asio.hpp>
using namespace std;
int main(int argc,char *argv[]) {

    boost::asio::io_service io;
    boost::asio::deadline_timer t(io,boost::posix_time::seconds(5));
    t.wait();
    std::cout<<" hello world\n";

    return 0;
}

but i have following error list

/usr/bin/make -f nbproject/Makefile-Debug.mk SUBPROJECTS= .build-conf
make[1]: Entering directory `/home/david/NetBeansProjects/Boost'
/usr/bin/make  -f nbproject/Makefile-Debug.mk dist/Debug/GNU-Linux-x86/boost
make[2]: Entering directory `/home/david/NetBeansProjects/Boost'
mkdir -p build/Debug/GNU-Linux-x86
rm -f build/Debug/GNU-Linux-x86/main.o.d
g++    -c -g -MMD -MP -MF build/Debug/GNU-Linux-x86/main.o.d -o build/Debug/GNU-Linux-x86/main.o main.cpp
mkdir -p dist/Debug/GNU-Linux-x86
g++     -o dist/Debug/GNU-Linux-x86/boost build/Debug/GNU-Linux-x86/main.o  
build/Debug/GNU-Linux-x86/main.o: In function `__static_initialization_and_destruction_0':
/usr/include/boost/system/error_code.hpp:205: undefined reference to `boost::system::get_system_category()'
/usr/include/boost/system/error_code.hpp:206: undefined reference to `boost::system::get_generic_category()'
/usr/include/boost/system/error_code.hpp:211: undefined reference to `boost::system::get_generic_category()'
/usr/include/boost/system/error_code.hpp:212: undefined reference to `boost::system::get_generic_category()'
/usr/include/boost/system/error_code.hpp:213: undefined reference to `boost::system::get_system_category()'
build/Debug/GNU-Linux-x86/main.o: In function `error_code':
/usr/include/boost/system/error_code.hpp:312: undefined reference to `boost::system::get_system_category()'
build/Debug/GNU-Linux-x86/main.o: In function `boost::asio::error::get_system_category()':
/usr/include/boost/asio/error.hpp:218: undefined reference to `boost::system::get_system_category()'
build/Debug/GNU-Linux-x86/main.o: In function `~posix_thread':
/usr/include/boost/asio/detail/posix_thread.hpp:69: undefined reference to `pthread_detach'
build/Debug/GNU-Linux-x86/main.o: In function `boost::asio::detail::posix_thread::join()':
/usr/include/boost/asio/detail/posix_thread.hpp:77: undefined reference to `pthread_join'
build/Debug/GNU-Linux-x86/main.o: In function `~posix_tss_ptr':
/usr/include/boost/asio/detail/posix_tss_ptr.hpp:61: undefined reference to `pthread_key_delete'
build/Debug/GNU-Linux-x86/main.o: In function `posix_tss_ptr':
/usr/include/boost/asio/detail/posix_tss_ptr.hpp:47: undefined reference to `pthread_key_create'
collect2: ld returned 1 exit status
make[2]: *** [dist/Debug/GNU-Linux-x86/boost] Error 1
make[2]: Leaving directory `/home/david/NetBeansProjects/Boost'
make[1]: *** [.build-conf] Error 2
make[1]: Leaving directory `/home/david/NetBeansProjects/Boost'
make: *** [.build-impl] Error 2
BUILD FAILED (exit value 2, total time: 5s)

pleas help what is happaned?

Answer 1

You need to link with the Boost.System library: -lboost_system Also you need to link with pthreads lib: -lpthread

Answer 2

The problem is not in your code, the problem is in the settings of the compiler (actually linker). You need to link to the Boost.System and pthread libraries. Usually it's done by passing -lboost_system, -lpthread to the linker options in your Makefile, or favorite IDE.