jsoncpp - can't define Json::Reader due to incomplete type

Question

Getting this error when I follow the simple code example from jsoncpp, that basically goes like

Json::Reader reader;

How to fix this? The type looks pretty complete to me but it's not like g++ is nice enough to tell me what is missing or anything.

error: aggregate Json::Reader reader has incomplete type and cannot be defined

Answer 1

Was supposed to #include <json.h>, not the individual classes I needed, per the README.txt.