将curlpp添加到cmake项目中

Question

我试图在curlcpp和cmake的帮助下在C++中做一个项目，但是我无法编译这个项目。

我是CMakeLists新手，很难理解如何添加使项目工作所需的内容。基本上，我通常会复制我在其他文章中可以找到的内容，而不会真正理解它们是如何工作的；教程和文档通常要么太基础，要么太复杂。更糟糕的是，我的印象是，每个库的添加方式不同，所以当有一个新的库添加时，我必须添加的唯一方法是搜索之前询问如何做的帖子。在这种情况下，我找不到任何帮助我的东西。

，下面是我所做的：

安装curlpp和curl后用自制

brew install curl
brew install curlpp

我写我的项目：

Cmakelists.txt：

cmake_minimum_required(VERSION 3.0)

project(stock_analysis)

set(CMAKE_CXX_FLAGS "-g -Wall -std=c++11")


######## BOOST STUFF ########
#DELETE NEXT LINE
set(Boost_NO_BOOST_CMAKE ON)

# set(Boost_USE_STATIC_LIBS        ON) # only find static libs
# set(Boost_USE_MULTITHREADED      ON)
# set(Boost_USE_STATIC_RUNTIME    OFF)
find_package(Boost COMPONENTS
                   filesystem
)

######## CURL STUFF ########
include(FindCURL)
find_package(CURL REQUIRED)
if(CURL_FOUND)
 message(STATUS "Found CURL version: ${CURL_VERSION_STRING}")
 message(STATUS "Using CURL include dir(s): ${CURL_INCLUDE_DIRS}")
 message(STATUS "Using CURL lib(s): ${CURL_LIBRARIES}")
else()
 message(FATAL_ERROR "Could not find CURL")
endif()




SET(HEADERS
   include
)

SET(SOURCE_FILES
  src/main.cpp
  src/analyse.cpp
  src/helpers.cpp
  src/simulation.cpp
  src/data.cpp
)

include_directories(${HEADERS}
                   ${Boost_INCLUDE_DIRS}
                   ${CURL_INCLUDE_DIRS}
)

add_executable(app ${SOURCE_FILES})

target_link_libraries(app
       ${Boost_LIBRARIES}
       ${CURL_LIBRARIES}
)

函数在data.cpp中(我基本上复制了curlcpp网页中的示例)：

#include "data.h"

#include <iostream>

#include <curlpp/cURLpp.hpp>
#include <curlpp/Easy.hpp>
#include <curlpp/Options.hpp>

using namespace curlpp::options;


void fetchData(){

  try
    {
    // That's all that is needed to do cleanup of used resources (RAII style).
        curlpp::Cleanup myCleanup;

        // Our request to be sent.
        curlpp::Easy myRequest;

        // Set the URL.
        myRequest.setOpt<Url>("http://example.com");

        // Send request and get a result.
        // By default the result goes to standard output.
        myRequest.perform();
  }

  catch( curlpp::RuntimeError &e )
    {
        std::cout << e.what() << std::endl;
    }

    catch( curlpp::LogicError &e )
    {
        std::cout << e.what() << std::endl;
    }
}

我所犯的错误：

Undefined symbols for architecture x86_64:
  "curlpp::OptionBase::OptionBase(CURLoption)", referenced from:
      curlpp::Option<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >::Option(CURLoption, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) in data.cpp.o
  "curlpp::OptionBase::~OptionBase()", referenced from:
      curlpp::Option<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >::Option(CURLoption, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) in data.cpp.o
      curlpp::Option<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >::~Option() in data.cpp.o
  "curlpp::UnsetOption::UnsetOption(char const*)", referenced from:
      curlpp::Option<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >::updateMeToOption(curlpp::OptionBase const&) in data.cpp.o
      curlpp::OptionTrait<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, (CURLoption)10002>::updateHandleToMe(curlpp::internal::CurlHandle*) const in data.cpp.o
      curlpp::Option<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >::getValue() const in data.cpp.o
  "curlpp::RuntimeError::~RuntimeError()", referenced from:
      curlpp::UnsetOption::~UnsetOption() in data.cpp.o
  "curlpp::libcurlRuntimeAssert(char const*, CURLcode)", referenced from:
      void curlpp::internal::CurlHandle::option<void*>(CURLoption, void*) in data.cpp.o
  "curlpp::Easy::perform()", referenced from:
      StockAnalysis::fetchData(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, bool const&) in data.cpp.o
  "curlpp::Easy::Easy()", referenced from:
      StockAnalysis::fetchData(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, bool const&) in data.cpp.o
  "curlpp::Easy::~Easy()", referenced from:
      StockAnalysis::fetchData(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, bool const&) in data.cpp.o
  "curlpp::Cleanup::Cleanup()", referenced from:
      StockAnalysis::fetchData(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, bool const&) in data.cpp.o
  "curlpp::Cleanup::~Cleanup()", referenced from:
      StockAnalysis::fetchData(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, bool const&) in data.cpp.o
  "curlpp::OptionBase::operator<(curlpp::OptionBase const&) const", referenced from:
      vtable for curlpp::OptionTrait<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, (CURLoption)10002> in data.cpp.o
      vtable for curlpp::Option<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > in data.cpp.o
  "typeinfo for curlpp::LogicError", referenced from:
      GCC_except_table0 in data.cpp.o
  "typeinfo for curlpp::OptionBase", referenced from:
      curlpp::Option<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >::updateMeToOption(curlpp::OptionBase const&) in data.cpp.o
      typeinfo for curlpp::Option<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > in data.cpp.o
  "typeinfo for curlpp::RuntimeError", referenced from:
      GCC_except_table0 in data.cpp.o
      typeinfo for curlpp::UnsetOption in data.cpp.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [app] Error 1
make[1]: *** [CMakeFiles/app.dir/all] Error 2
make: *** [all] Error 2

我之前跟踪了下一个线程：使用CMake链接项目中的curl

将curlcpp添加到cmakelist中的target_link_libraries()只会出现另一个错误：

ld: library not found for -lcurlpp
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [app] Error 1
make[1]: *** [CMakeFiles/app.dir/all] Error 2
make: *** [all] Error 2

顺便说一句，我不明白为什么curlcpp出现在没有传统的cmakelist符号${Some_variable}的地方。

Answer 1

使用curlpp，如下所示(最低代码)：

cmake_minimum_required(VERSION 3.14)
project(testCurlPP LANGUAGES CXX)
set(CMAKE_INCLUDE_CURRENT_DIR ON)
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

include(FindPkgConfig)
pkg_check_modules(CURLPP REQUIRED curlpp)

add_executable(testCurlPP
  main.cpp
)
target_link_libraries(testCurlPP
    ${CURLPP_LDFLAGS}
    )

注意:在项目中使用curlpp之前，不要忘记构建和安装curlpp。

构建(最后发布的) 柯尔普

mkdir build
cd build
cmake ..
make -j8
sudo make install

将其位置添加到环境变量中：

LD_LIBRARY_PATH=/usr/local/lib