Reading Json file with root

Newbie
1

Hello,

I am trying to read a json file using the library nlohmann-json. My code is the following:

#include "/usr/local/Cellar/nlohmann-json/3.11.2/include/nlohmann/json.hpp"
#include <iostream>
void ReadJson()
{
    std::ifstream param_file("params.json");
    nlohmann::json Parameters = nlohmann::json::parse(param_file);
}

Which throws the following error:

libc++abi: terminating with uncaught exception of type cling::InvalidDerefException: Trying to access a pointer that points to an invalid memory address.

I do not know if it is relevant, but when trying to include nlohmann-json I first tried with:
#include "nlohmann/json.hpp"

But root did not recognize it, so I had to install the library separately and write the full path to the library location.

Thanks in advance.

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ROOT Version: 6.28/06
Platform: macOS Monterrey 12.6.3
Compiler: Not Provided

2

Maybe add after this line, for security:
if(!param_file.good()) return;

3

But tI do want to read the file, so the execution of that line is needed.

4

That lines adds a security: if the file name is incorrect or not found, it will exit instead of crashing. So you have to fix the filename or path so that it finds it correctly.

5

Actually, the file is found correctly (param_file.good()) returns true so I believe the issue must be coming from the nlohmann-json library.

6

Mmm maybe try to share the json file with us, or try to debug it yourself with:

7

The content of the json file is as simple as:

{
  "a": 1
}

I have tried to run this very same code on another laptop and it does work, so I guess it might be related to the ROOT installation. By the way, I am not allowed to modified the original post anymore, but there is a mistake with the ROOT version, it is 6.26/06.