Using the QJson library

Question

I know it's a stupid question, but still.

I want to use the QJson library in my project. I've downloaded the tarball from the official site (probably need to mention that I'm under 64-bit Ubuntu 12.04). The INSTALL file has the following instructions

  mkdir build
  cd build
  cmake -DCMAKE_INSTALL_PREFIX=_preferred_path_ ..
  make
  make install
  /sbin/ldconfig, if necessary

which I followed precisely. I've got the /include, /lib and share folders of QJson added to my /usr/local.

After that, I open my IDE (which is QtCreator), and make a test project with the following simple code:

#include <QVariant>
#include <qjson/serializer.h>

int main(int argc, char *argv[])
{
    QJson::Serializer s;
    QVariantMap map;
    map["hello"] = QVariantList() <<"t1"<<"t2";
    QByteArray json = s.serialize(map);
}

The #include is handled fine, all the types are recognized, the auto-complete for the QJson classes works fine. However, when trying to compile, I'm getting this (full path removed for readability):

<...>/QJsonTest/main.cpp:15: undefined reference to `QJson::Serializer::Serializer()'
<...>/QJsonTest/main.cpp:18: undefined reference to `QJson::Serializer::serialize(QVariant const&)'
<...>/QJsonTest/main.cpp:18: undefined reference to `QJson::Serializer::~Serializer()'
<...>/QJsonTest/main.cpp:18: undefined reference to `QJson::Serializer::~Serializer()'
collect2: ld returned 1 exit status

What's the reason, and how do I make it work?

Answer 1

You are hitting linker (not compiler) errors. You need to add the path to your QJson library files with a -L option