我有一个使用boost（程序选项模块）的C ++代码示例，如下所示：
#include <iostream>
#include <boost/program_options/options_description.hpp>
#include <boost/program_options/parsers.hpp>
#include <boost/program_options/variables_map.hpp>
namespace po = boost::program_options;
int main(int argc, const char* argv[]){
po::options_description description("MyTool Usage");
description.add_options()
("help,h", "Display this help message")
("version,v", "Display the version number");
po::positional_options_description p;
po::variables_map vm;
po::store(po::command_line_parser(argc, argv).options(description).positional(p).run(), vm);
po::notify(vm);
if(vm.count("help")){
std::cout << description;
return 0;
}
if(vm.count("version")){
std::cout << "MyTool Version 1.0" << std::endl;
return 0;
}
return 0;
}
我尝试使用cmake进行编译。相应的CMakeLists.txt文件如下所示：
cmake_minimum_required(VERSION 2.6)
set(CMAKE_CXX_LINK_FLAGS "-std=c++11 -g -Wall -fsigned-char -lboost_program_options-mt")
set(BOOST_ROOT /opt/local/include/boost)
set(BOOST_LIBRARYDIR /opt/local/lib)
find_package(Boost COMPONENTS program_options system filesystem REQUIRED)
include_directories(${BOOST_INCLUDE_DIR})
link_libraries(${BOOST_LIBRARIES})
add_executable(testboostpo testboostpo_simple.cpp)
target_link_libraries(testboostpo ${Boost_LIBRARIES})
尽管cmake .似乎成功了，并且它还能检测到我通常使用的所有boost模块（程序选项，系统，文件系统），
$ cmake .
-- The C compiler identification is GNU 5.5.0
-- The CXX compiler identification is GNU 5.5.0
-- Checking whether C compiler has -isysroot
-- Checking whether C compiler has -isysroot - yes
-- Checking whether C compiler supports OSX deployment target flag
-- Checking whether C compiler supports OSX deployment target flag - yes
-- Check for working C compiler: /opt/local/bin/gcc-mp-5
-- Check for working C compiler: /opt/local/bin/gcc-mp-5 -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Checking whether CXX compiler has -isysroot
-- Checking whether CXX compiler has -isysroot - yes
-- Checking whether CXX compiler supports OSX deployment target flag
-- Checking whether CXX compiler supports OSX deployment target flag - yes
-- Check for working CXX compiler: /opt/local/bin/g++-mp-5
-- Check for working CXX compiler: /opt/local/bin/g++-mp-5 -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Boost version: 1.66.0
-- Found the following Boost libraries:
-- program_options
-- system
-- filesystem
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/params/libraries/coding_interview/every_test/boost_test
下一步make失败，并显示以下错误：
$ make
Scanning dependencies of target testboostpo
[ 50%] Building CXX object CMakeFiles/testboostpo.dir/testboostpo_simple.cpp.o
[100%] Linking CXX executable testboostpo
ld: library not found for -lboost_program_options-mt
collect2: error: ld returned 1 exit status
make[2]: *** [testboostpo] Error 1
make[1]: *** [CMakeFiles/testboostpo.dir/all] Error 2
make: *** [all] Error 2
为程序选项链接boost库似乎存在问题。但是，我可以看到该库已安装在/opt/local/lib/libboost_program_options-mt.dylib
或者，我也尝试隔离编译，但同样失败。
$ g++ -L/opt/local/lib testboostpo_simple.cpp -lboost_program_options-mt
Undefined symbols for architecture x86_64:
"boost::program_options::to_internal(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)", referenced from:
std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > boost::program_options::to_internal<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >(std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&) in ccg8tggM.o
ld: symbol(s) not found for architecture x86_64
collect2: error: ld returned 1 exit status
$ g++ -L/opt/local/lib testboostpo_simple.cpp /opt/local/lib/libboost_program_options-mt.dylib
Undefined symbols for architecture x86_64:
"boost::program_options::to_internal(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)", referenced from:
std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > boost::program_options::to_internal<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >(std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&) in ccg8tggM.o
ld: symbol(s) not found for architecture x86_64
collect2: error: ld returned 1 exit status
我正在使用gcc5，boost 1.66和cmake 3.12（它们均使用macports安装）。
boost头文件位于以下位置：
/opt/local/include/boost/
Boost库文件位于以下位置：
/opt/local/lib
这里是否有人知道尽管提供了路径，但可能导致boost链接仍然失败的原因是什么？这里还有其他遗漏或错误指定的内容吗？
谢谢
答案 0 :(得分：1)
因为您已经使用了CMAKE_CXX_LINK_FLAGS，而cmake会首先检查它而不是使用target_link_libraries，如果您想自己做，则还需要添加-L / opt / local / lib，更简单的方法是让cmake为您做。以下是我的示例：
cmake_minimum_required(VERSION 2.6)
project(server CXX)
set(CXX_FLAGS
-g
-Wall
)
# set(Boost_NO_SYSTEM_PATHS ON)
set(BOOST_ROOT /mnt/d/Code/boost)
set(BOOST_LIBRARYDIR /mnt/d/Code/boost/stage/lib)
find_package(Threads REQUIRED)
find_package(Boost 1.68.0 COMPONENTS program_options REQUIRED)
file(GLOB SRC
"*cpp*"
)
if(Boost_FOUND)
include_directories(${Boost_INCLUDE_DIRS})
message(${Boost_PROGRAM_OPTIONS_LIBRARIES})
add_executable(main ${SRC})
target_link_libraries(main Threads::Threads ${Boost_PROGRAM_OPTIONS_LIBRARIES})
endif()
此外，如果单独构建它，则应首先编译该对象然后进行链接，否则它可能会变成未定义的引用。对于您来说，应该在最后一个链接，将链接放在前面或后面时结果会有所不同，很抱歉，我不明白为什么会发生这种情况。
答案 1 :(得分：0)
您似乎正在尝试将32位库与64位版本链接。提示是ld: symbol(s) not found for architecture x86_64。
链接库要求您匹配确切的构建类型。这是有关链接过程的更多信息。
https://www.boost.org/doc/libs/1_63_0/more/getting_started/windows.html