Parsing from stream leads to an array

[matsbror]

Hello,

I parse the following file from a stream:

{
  "anInt": 500,
  "aString": "fixed"
}

Then I send it to an output stream with dump(4), which yields the following output:

[
    {
        "aString": "fixed",
        "anInt": 500
    }
]

It has become embedded in an array. Do you know why and how can I get around it?
If it is consistent, I can of course deal with it as it is.

[nlohmann]

This is odd. Can you please provide the code that you execute for this?

[matsbror]

#include <iostream>
#include <fstream>
#include <cstdio>

#include "json.hpp"

using json = nlohmann::json;

json readJsonFile(const std::string & fileName){
    std::ifstream jsonFile(fileName);
    return json::parse(jsonFile);
}
int main() {
    json bidConfig { readJsonFile("../test.json") };
    std::cout << bidConfig.dump(4) << std::endl;
    return 0;
}

`

[matsbror]

edit the file name to where you have your json

[matsbror]

It seems to be related to that I pass the json document as return value from the readJsonFile function. If I parse it and use it in the same function, there is no array.

I can also pass the document as reference to the function that reads it and return it that way. It seems as it is the return value that is not working and it is not related to parsing.

[matsbror]

OK, it is related to the universal initalization. It takes it as an initializer list and thus makes an array out of it. If I change:

json bidConfig { readJsonFile("../test.json") };

to

json bidConfig = readJsonFile("../test.json");

it works as expected.

[nlohmann]

Yes, that is it. We use the braces as array literals, e.g. {1,2,3}.