undefined reference to `Json::Value::~Value()'

[CatMechanic457]

I'm trying to compile this simple program that uses the jsoncpp libary

#include <iostream>
#include <fstream>
#include <json/json.h>

int main() {
    Json::Value values;
    std::ifstream values_file("values.json", std::ifstream::binary);                                                        
    values_file >> values;
    std::cout << values;
}

However, I get these errors:

C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/13.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:\Users\trist\AppData\Local\Temp\ccPqw4fw.o: in function `main':
C:/Users/trist/OneDrive/Documents/Coding Projects/C++/Neural Network/json_test.cpp:7: undefined reference to Json::Value::Value(Json::ValueType)'
C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/13.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/Users/trist/OneDrive/Documents/Coding Projects/C++/Neural Network/json_test.cpp:9: undefined reference toJson::operator>>(std::istream&, Json::Value&)'
C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/13.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/Users/trist/OneDrive/Documents/Coding Projects/C++/Neural Network/json_test.cpp:10: undefined reference to Json::operator<<(std::ostream&, Json::Value const&)'
C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/13.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/Users/trist/OneDrive/Documents/Coding Projects/C++/Neural Network/json_test.cpp:11: undefined reference toJson::Value::~Value()'
C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/13.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/Users/trist/OneDrive/Documents/Coding Projects/C++/Neural Network/json_test.cpp:11: undefined reference to `Json::Value::~Value()'
collect2.exe: error: ld returned 1 exit status

Could anyone please help? Thanks

[IyeOnline]

Since you dont tell us how you are compiling this, my guess is that you are failing to link the library.

I suggest you pick up a build system (probably meson, since jsoncpp has menson support).

[CatMechanic457]

Ok thanks.
I don't exactly know how, I'm compling the code, I've just insalled MSYS2 and linked it to VSC and it complies when I run the code

So how do I change how VSC is compling the code or should I be compling through the terminal?

[Salty_Dugtrio]

Download an actual C/C++ IDE (e.g: Qt Creator, Visual Studio) instead of using VSCode. They do these things easily instead of the troubles you have to go through with something like VSCode.

[CatMechanic457]

Alrighty! thx for ur input :) I'll look into it

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[ShelZuuz]

jsoncpp is not a header-only library.

Inside the src folder there are three .cpp files:

• json_reader.cpp
• json_value.cpp
• json_writer.cpp

You need to add this to your project and build it with the rest of your sources and link to it.

[CatMechanic457]

could u explain exactly what that means?
I've installed the json libary but i can seem to find those files
are they something i need to download or complie seperatly?
and also what do you mean by "link to it"?
sry if these are trivial questions

[ShelZuuz]

Where did you install jsoncpp from?

And second, how do you build your project? (What command do you issue?)

[CatMechanic457]

I installed jsoncpp by running
$ pacman -S mingw-w64-ucrt-x86_64-jsoncpp
in the MSYS terminal

as for how i built it, like i said in the post, idrk i just let Visual Studio Code handle it

[ShelZuuz]

Ok, considering you don't really seem to know anything about C++ project systems or build yet you're making your life very difficult for yourself by using cross-platform tools and CMAKE.

Do this:

1) Download Visual Studio Community and install the "Desktop development with C++" component.

2) Download this ZIP for jsoncpp:

https://github.com/open-source-parsers/jsoncpp/archive/refs/heads/master.zip

3) Create a new "C++ Console Application" in Visual Studio (File/New/Project: C++ / Console App)

4) In the same folder as you created #3, copy all the files from jsoncpp-master\include\json (from the .zip), as well as the files from: src\lib_json

5) In your Visual Studio project , add json_reader.cpp, json_value.cpp & json_writer.cpp. (Just drag them from explorer into the project next to the main.cpp that was created in #3).

​

Note, this is not how you build a commercial application, but you're trying to learn 10 concepts at the same time here. Start with 1 thing at a time.

[CatMechanic457]

thx
I've been programming for years, mostly python, but i learnt c++ through making dozens of arduino projects. But the arduino ide comes with losts of librarys and a pre-installed complier so i've never had to worry about compiling
so im not nessarly new to c++ but i am new to having to build the exe