1

In the project I'm working on, I'm trying to use the curlpp library to make a simple html GET request. I pass the cpp file to clang++ with the following options:

clang++ -std=c++11 -stdlib=libc++ -I /usr/local/Cellar url_test.cpp

I then get these errors:

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 url_test-541b93.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 url_test-541b93.o
      curlpp::Option<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >::~Option() in url_test-541b93.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 url_test-541b93.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 url_test-541b93.o
      curlpp::Option<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >::getValue() const in url_test-541b93.o
  "curlpp::RuntimeError::~RuntimeError()", referenced from:
      curlpp::UnsetOption::~UnsetOption() in url_test-541b93.o
  "curlpp::libcurlRuntimeAssert(char const*, CURLcode)", referenced from:
      void curlpp::internal::CurlHandle::option<void*>(CURLoption, void*) in url_test-541b93.o
  "curlpp::Easy::perform()", referenced from:
      _main in url_test-541b93.o
  "curlpp::Easy::Easy()", referenced from:
      _main in url_test-541b93.o
  "curlpp::Easy::~Easy()", referenced from:
      _main in url_test-541b93.o
  "curlpp::Cleanup::Cleanup()", referenced from:
      _main in url_test-541b93.o
  "curlpp::Cleanup::~Cleanup()", referenced from:
      _main in url_test-541b93.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 url_test-541b93.o
      vtable for curlpp::Option<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > in url_test-541b93.o
  "typeinfo for curlpp::LogicError", referenced from:
      GCC_except_table0 in url_test-541b93.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 url_test-541b93.o
      typeinfo for curlpp::Option<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > in url_test-541b93.o
  "typeinfo for curlpp::RuntimeError", referenced from:
      GCC_except_table0 in url_test-541b93.o
      typeinfo for curlpp::UnsetOption in url_test-541b93.o
  "_curl_easy_setopt", referenced from:
      void curlpp::internal::CurlHandle::option<void*>(CURLoption, void*) in url_test-541b93.o
ld: symbol(s) not found for architecture x86_64

which I think means that the compiler cannot find any of the curlpp libraries.

Here's the code I'm trying to run:

  1 #include <string>
  2 #include <sstream>
  3 #include <iostream>
  4 #include <curlpp/cURLpp.hpp>
  5 #include <curlpp/Easy.hpp>
  6 #include <curlpp/Options.hpp>
  7 #include <fstream>
  8 
  9 using namespace curlpp::options;
 10 
 11 int main(int, char **)
 12 {
 13     try
 14     {
 15         curlpp::Cleanup testCleanup;
 16         curlpp::Easy miRequest;
 17         miRequest.setOpt<Url>("http://www.wikipedia.org");
 18         miRequest.perform();
 19     }
 20     catch(curlpp::RuntimeError & e)
 21     {
 22         std::cout << e.what() << std::endl;
 23     }
 24     catch(curlpp::LogicError & e)
 25     {
 26         std::cout << e.what() << std::endl;
 27     }
 28 
 29     return 0;
 30 }

I'm running macOS Sierra 10.12.4 with Xcode command line tools and homebrew installed. I homebrew'd the curlpp library. I know that someone else was able to compile this project on Ubuntu 16.04 using gcc, so I think the issue is to do with macOS.

I'm quite new to cpp, so any help would be greatly appreciated!

Jack Westmore
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2 Answers2

1

You have to tell the compiler which libraries to link with your executable. In your case, the issue is solved by adding options -lcurlpp -lcurl.

By the way, the path you provide is not correct since headers actually reside in /usr/local/Cellar/curlpp/[insert version here]/include. Anyways, this compiles fine without adding include search path for libraries installed via homebrew since it automatically creates symlinks in /usr/local/include, which is one of default places for a compiler to search.

Volodymyr Lashko
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  • Thanks, if I try `clang++ -std=c++11 -stdlib=libc++ -lcurlpp -lcurl` I then get the following: `url_test.cpp:4:10: fatal error: 'curlpp/cURLpp.hpp' file not found` - any suggestions? – Jack Westmore Jun 16 '17 at 10:21
  • Ok, I finally got this working by uninstalling and then reinstalling and relinking the curlpp libraries. Phew! – Jack Westmore Jun 16 '17 at 10:40
0

Your problem is that you are not linking the library you use. Add the library and you should be good.

Jesper Juhl
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