Third party library causes 'undefined reference' compiler errors?

Question

I'm a newcomer to C++. I am creating a simple GUI application that uses libcurlpp to visit a webpage, like so:

#include <sstream>
#include <string>

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

using curlpp::Cleanup;
using curlpp::options::Url;

using std::ostringstream;
using std::string;

string MainWindow::getstr(const string &uri)
{
    Cleanup cleanup;

    ostringstream stream;
    stream << Url(uri);

    return stream.str();
}

However, when I compile the code, I get about 20 different linker errors saying that all the references to curlpp are undefined. Sure enough, when I go to the include directories, I see only header files.

If it matters, I'm on Ubuntu 14.04 and I installed libcurlpp by running an apt-get install libcurlpp-dev . Is there anything else I have to do to point the compiler to the .cpp / .o files and get rid of the undefined references?

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Disclaimer: Yes, I did read this , and no, it isn't relevant to my question because it does not talk specifically about dealing with third-party libraries and where the implementation files ( .cpp and .o ) are installed on my system.

Answer 1

如果没有任何libcurlpp.a或libcurlpp.so ，那么我建议您再次下载libcurlpp-dev ，程序包中有库文件。

Answer 2

You have to add the library to the linker. If you are using Qt Creator, write

LIBS += -lcurlpp

in the .pro file.

EDIT : You have to add all libraries this way. As the comment says, in the case of cURL++, which is a wrapper for the cURL C library, you'll also need -lcurl .