Repository navigation
Cant modify existing numbers inside a json object #557
Description
Say for example I have something like
json j;
j["num"] = 0;I can not do something like
j["num"] += 1;
as it gives me this error on runtime:
terminate called after throwing an instance of 'std::domain_error'
what(): cannot use push_back() with number
I tried simplifying it to
j["num"] = j["num"] + 1;
but that gives me this error at compile time:
error: no match for 'operator+' (operand types are 'nlohmann::basic_json<>::value_type {aka nlohmann::basic_json<>}' and 'int')|
Activity
gregmarr commentedon Apr 17, 2017
j["num"]is ajsonobject, not anint. You need toget()theintout of it before you can add 1 to it and assign it back again.nlohmann commentedon Apr 19, 2017
In addition to @gregmarr s remarks:
+=is an overload forjson::push_backand can only be called on a JSON array. And indeed the+operator has no overload forjsonandint.To increment
j["num"], you need to callor
nlohmann commentedon Apr 22, 2017
@AMScaglione Does this work for you?
AMScaglione commentedon Apr 23, 2017
nlohmann commentedon Apr 23, 2017
No problem.