I'm just getting started with Boost for the first time, details:
My code now compiles, and I pointed my project at the boost libraries (after having built x64 libs) and got past simple issues, now I am facing a linker error:
2>BaseWebServer.obj : error LNK2001: unresolved external symbol "class boost::system::error_category const & __cdecl boost::system::get_system_category(void)" (?get_system_category@system@boost@@YAAEBVerror_category@12@XZ) 2>BaseWebServer.obj : error LNK2001: unresolved external symbol "class boost::system::error_category const & __cdecl boost::system::get_generic_category(void)" (?get_generic_category@system@boost@@YAAEBVerror_category@12@XZ)
any ideas?
I added this define: #define BOOST_LIB_DIAGNOSTIC
And now in my output I see this:
1>Linking to lib file: libboost_system-vc90-mt-1_38.lib 1>Linking to lib file: libboost_date_time-vc90-mt-1_38.lib 1>Linking to lib file: libboost_regex-vc90-mt-1_38.lib
which seems to indicate it is infact linking in the system lib.
So when we try to assign it a value in the main function, the linker doesn't find the symbol and may result in an “unresolved external symbol” or “undefined reference”. The way to fix this error is to explicitly scope the variable using '::' outside the main before using it.
To fix this issue, add the /NOENTRY option to the link command. This error can occur if you use incorrect /SUBSYSTEM or /ENTRY settings in your project. For example, if you write a console application and specify /SUBSYSTEM:WINDOWS, an unresolved external error is generated for WinMain .
Answer. Unresolved external references occur when the symbol for a function or global variable is referenced in a program, but none of the object files or libraries specified in the link step contain a definition for that symbol.
I solved the problem. I had built 32-bit libraries when I had intended to build 64-bit libraries. I fixed up my build statement, and built 64-bit libraries, and now it works.
Here is my bjam command line:
C:\Program Files (x86)\boost\boost_1_38>bjam --build-dir=c:\boost --build-type=complete --toolset=msvc-9.0 address-model=64 architecture=x86 --with-system
#include <boost/system/config.hpp>
In my case, BOOST_LIB_DIAGNOSTIC did not show system being automatically linked in. I resolved this by simply including boost/system/config.hpp.
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