Use this tag for questions related to nlohmann JSON C++ library
nlohmann JSON is a header-only JSON class for Modern C++ (C++11)
Latest release: 3.9.1 released on 2020-08-06
See the github project
Questions tagged [nlohmann-json]
248 questions
0
votes
1 answer
Having trouble opening a json file in C++
I am trying to open a json file that I will be working with in C++. Code that I have used successfully before fails to open the file. I am using Visual Studio 2017 on Windows 10 Pro with JSON for Modern C++ version 3.5.0.
I have a very simple…
Al G
- 115
- 4
- 10
0
votes
1 answer
nlohmann parsing a json file without knowing keys
I'm using nlohmann/json library to use json in cpp. I have a Json::Value object and I would like to go through my json data by exploring the keys without knowing them. I came across the documentation but only found the object["mySuperKey"] method to…
pipou
- 270
- 3
- 15
0
votes
0 answers
How to see which line while parsing json source caused the exception?
I have JSON files with hundreds of lines, but when there is an error that causes a parsing exception, the library returns a character position, not a line number.
Line number would be hugely helpful since most text editors will show you, or take you…
Dan
- 101
- 1
0
votes
2 answers
JSON parser for C++
I'm trying to parse Json file and store the data into 2D array or vector. The Json file looks like this:
{"n" : 2,
"x" : [[1,2],
[0,4]]}
And this is what my code looks like and but I keep getting "json.exception.parse_error.101"…
5a9ar
- 1
- 2
0
votes
0 answers
How to search array of json objects and return matching object using nlohmann-json
Imagine there is an array of account objects
[
{"account_number":1,"customer_name":"John"},
{"account_number":2,"customer_name":"Sally"}
]
I want to write a method that takes in an account number and returns the matching account object. I…
pd227
- 1
0
votes
1 answer
How to add object member in array?
I have json file like this.
Use nlohmann.
{"Fans": [
{
"MemberID": "0",
"Name": "Fan 0 ABC",
"Reading": 30
},
{
"MemberID": "1",
"Name": "Fan 1 ABC",
…
Toby
- 3
- 3
0
votes
1 answer
How do I solve exception generated due to string to json conversion?
I am trying to understand JSON to string and string to JSON conversion using nlohmann framework for JSON library in C++. However I am getting problem with exception generated and I am not understanding the reason why it is being generated.
The…
prashanth kumar
- 17
- 6
0
votes
2 answers
Creating a json database with user input
I need to create my .json array to look like this:
{
"airports": [{
"address": "Horley, Gatwick RH6 0NP, UK",
"city": "London",
"shortVersion": "LGW"
},
{
"address": "Marupe, LV-1053",
…
Supreez
- 3
- 1
0
votes
1 answer
C++ Json Key variable issue
I'm having an issue with my code for jSon object conversion. I am trying to write a loop that takes in a vector and if the vector has an inversion then store that in a jSon Object. The only real problem I am having is the correct output. I am…
user3712347
- 31
- 6
0
votes
1 answer
Cross-compilation errors Visual studio C++
I recently converted my Windows C++ application to a Linux c++ application and use a Windows subsystem with Debian to cross-compile to Linux. However, I get the following error by using the json library by nlohmann
no match for 'operator-' (operand…
Thomas Wagenaar
- 6,489
- 5
- 30
- 73
0
votes
1 answer
Why nlohmann/json serialize "null" instead of "0" on double?
Let say I partially init a native double array in C++ and serialize it with nlohmann/json:
const int numPoints = 10;
double mLengths[numPoints];
for (int i = 0; i < 5; i++) {
mLengths[i] = i + 0.1 * i;
}
nlohmann::json…
markzzz
- 47,390
- 120
- 299
- 507
0
votes
2 answers
How to deserialize an array?
I'm using the nlohmann::json library to serialize/deserialize elements in json.
Here's how I serialize a C++ array of double:
double mLengths[gMaxNumPoints] = { 1.0, 2.0, 3.0, 4.0, 5.0 };
...
nlohmann::json jsonEnvelope;
jsonEnvelope["lengths"] =…
markzzz
- 47,390
- 120
- 299
- 507
0
votes
1 answer
How to assign derived class from base ptr to nlohmann::json
I am playing with some kind of shared object framework.
It is using nlohmann::json to provide message passing and configuration and loads message handlers and datasources depending of the json config.
As I am using value classes, which all derive…
Plurax
- 44
- 6
0
votes
1 answer
Nlohmann json get with type deduction
With nlohmann::json an object can be parsed using a couple different expressions:
type x = json;
type x; x = json.get();
However, type x; x = json; doesn't work, because that would require adding a new assignment operator for type.
I find…
SU3
- 5,064
- 3
- 35
- 66
0
votes
1 answer
nlohmann creating multilevel objects dynamically
I need to create the following structure but I am struggling to do this using json.
{
"ParentTree": [{
"Name": "Name3",
"children": [{
"Name": "Name2",
"children": [{
"Name": "Name1",
…
Arun
- 2,247
- 3
- 28
- 51