question about boost asio

问题

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?

回答1:

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.

回答2:

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

回答3:

You need to right click your project root folder and select properties.

From there, you need to select 'Linker' in the left pane and the 'Libraries' option field is there. You need to browse your system till you find the libboost_system.a binary. Usually at /usr/local/lib.

If you cant find the file you are after you may not have compiled the source for those libraries yet. Check out either http://ubuntuforums.org/showthread.php?t=1180792 or the getting started documentation included in the boost tar package.

回答4:

For future reference to anyone with the same problem: In netbeans right click the project -->Properties -> C++ Compiler and at the bottom there's an option for "Aditional arguments" pass in the -lboost_system option. Note: -lboost_system must be defined or you'll get errors

来源：https://stackoverflow.com/questions/3641761/question-about-boost-asio