How to know the object's key ?

[ZyaCon]

Hello,

When receiving a json object, how can I check if the first element from de JSON is "pi" ?
From your exemple :

json j2 = {

    {"pi", 3.141},
    {"happy", true},
    {"name", "Niels"},
    {"nothing", nullptr},
    {"answer", {
        {"everything", 42}
    }},
    {"list", {1, 0, 2}},
    {"object", {
        {"currency", "USD"},
        {"value", 42.99}
    }}
};

Thanks

[nlohmann]

This is not possible. The value 3.141 has no connection to its parent object.

[ZyaCon]

Oh, I can't know wich is the first element from a json object ?
And how can I check if a specific key exists in the json object?

[nlohmann]

You can access the first element with front (https://nlohmann.github.io/json/api/basic_json/front/).

You can use contains (https://nlohmann.github.io/json/api/basic_json/contains/) to check if an object contains a key.

[ZyaCon]

I didn't see your api !
Thanks for the answers, i'm a beginner with c++ haha