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
Casting of json value results in std::domain_error
I am trying to iterate over an array in a json file to retrieve an entry with an ID. The value that I want to compare it to is not a string (the json default type), but an uint64_t. For testing purposes, I wrote this simplified example:
#include…
DocDriven
- 3,726
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2 answers
How to convert nlohmann json to uint8_t array?
I would like convert my created json object to array of uint8_t[1000]. I tried something like this:
nlohmann::json j_file;
j_file["number"] = 2;
j_file["example"] = "dog";
uint8_t parsed_json[1000] ={0};
auto str =…
Creatorek
- 9
- 3
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votes
1 answer
Why is decltype for nlohmann json object different?
How do I extract information of underlying datatype from nlohmann object?
Since the values are stored as primitive datatypes in the json why don't it give the output like a and b below?
I see typedef as below for ordered…
Sreeraj Chundayil
- 5,548
- 3
- 29
- 68
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1 answer
Who deletes previous nlohmann json object resources when value is replaced?
I have a key and I want to change the value of the key with another json object.
json newjs = ...;
json tempjs = ...;
newjs["key"] = tempjs["key"];
What will happen to the data existed in newjs["key"] previously?
Will nlohmann class…
Sreeraj Chundayil
- 5,548
- 3
- 29
- 68
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0 answers
Parsing Json value after using the nlohmann:Json Convertor for map to Json
I am using the nlohmann::Json to converting the map to stringJson in c++ side. using that stringjson, I have passed entire Json to C# side using PINVOKE.
I am struggling to parse the Json when folder is having multiple data.
For…
Satyam Mishra
- 333
- 3
- 10
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0 answers
scalable way to create new instance of a specific class/subclass from JSON input in C++
I am looking for a way to load a specific class/subclass type based on JSON input. For example, I have the following JSON file
"type" : "RenderVertices"
"RenderComponent": {
"vertex": {
"xcoords" : [0, 1, 1, 0]
"ycoords" : [0, 0, 1, 1]
…
InterdimensionalCat
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- 3
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1 answer
Fetching api with nlohmann/json
I want to use api with c++ and when I searched I found nlohmann/json library it looks really popular but no one talks about how to get the array that fetch function provides . How can I get the information from the api as variables in my cpp file
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Adding XPointer/XPath searches to ALL(?) C++ JSON libraries, is it doable?
Is it possible to extend all(?) existing C++ JSON libraries with XPath/XPointer or subset with just one C++ implementation? At least those with iterators for object and array values?
I have reviewed three C++ JSON libraries (reviewing nlohmann,…
Per Ghosh
- 449
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- 10
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0 answers
Process big size of file and memory management
I tried to read and parse (using nlohmann library) a Json file that is almost 90MB using this code:
std::ifstream ifs("data.json");
json jsonFile = json::parse(ifs);
The Json file to parse has almost 14000 array elements that need to be…
Ali Sepehri-Amin
- 493
- 1
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- 18
0
votes
0 answers
CMake "find_package" found the package but the compiler cant find the include files
I'm trying to build a program that uses nlohmann::json but I'm having an issue with the includes. As per the instructions I'm using find_package(nlohmann_json 3.9.0 REQUIRED) and CMake will find the package but when I build I get an error telling…
dominique120
- 1,170
- 4
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- 31
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1 answer
C++ Nlohman::json third-party support not compiling
I'm using nlohmann::json to (de)serialize some C++ objects in JSON. I haven't yet understood how to set up the code to work with a third-party library (SoapySDR). My code is in the global namespace in this example, while the SoapySDR code is in…
Richard Groot
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- 1
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0 answers
Is it possible to serialize nested/complex classes with nlohmann/json?
I would like to use nlohmann/json to serialize a tree, but I am unsure if nlohmann/json provides the necessary features.
Features about which I am unsure:
Serialization of nested types. I am serializing a tree after all...
Serialization of…
User12547645
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- 69
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0 answers
How to solve this Floating Point expection: 8 error
This program is suppose to take a json in the format of a dict. The keys are zipcodes and the values are vectors of rent prices.
When i run it using g++ I get a floating point exception 8: error. To my knowledge that error only triggers if the value…
Josh W
- 29
- 4
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0 answers
Serializing cv::Mat with nlohmann/json lib
I would like to serialize my own Camera class with the nlohmann/json library:
class Camera
{
private:
std::string name_;
std::string camera_calibration_filename_;
cv::Mat intrinsics_;
cv::Mat distortion_;
public:
Camera() =…
Hannes
- 1
0
votes
1 answer
How to parse Json file only as a raw string value in cpp. I am using nlohmann json library for parsing
I have a json file
which looks something like this
{accessvalue: xyz-verylongvalue ,Type:abc}
I am parsing it using nlohmann json as given below:
std::ifstream ifs(PATH);
auto config= json::parse(ifs);
if (config.find("accessvalue")!=config.end()){…
Sid
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