nlohmann json, writing to json file
To write data to a JSON file using the nlohmann json library in C++, you can follow these steps:
- Include the necessary headers: Begin by including the necessary headers for working with nlohmann json:
#include <iostream>
#include <fstream>
#include <nlohmann/json.hpp>
The <iostream>
header is used for input/output operations, <fstream>
is used for working with file streams, and <nlohmann/json.hpp>
is the header file for the nlohmann json library.
- Create a JSON object: Next, create a JSON object using the
nlohmann::json
class:
nlohmann::json jsonData;
This object will hold the data that you want to write to the JSON file.
- Populate the JSON object: Populate the JSON object with the desired data. You can add values to the JSON object using the
[]
operator:
jsonData["name"] = "John Doe";
jsonData["age"] = 30;
In this example, we are adding a "name" key with the value "John Doe" and an "age" key with the value 30 to the JSON object.
- Open a file stream: Open a file stream to create or open the JSON file for writing:
std::ofstream file("data.json");
Here, we are opening a file stream named "file" with the filename "data.json". If the file does not exist, it will be created. If it already exists, its contents will be overwritten.
- Write the JSON data to the file: Use the
<<
operator to write the JSON data to the file:
file << jsonData;
This will write the JSON data stored in the jsonData
object to the file.
- Close the file stream: Close the file stream to release the resources:
file.close();
It is good practice to close the file stream after you have finished writing the data.
And that's it! Following these steps, you can write data to a JSON file using the nlohmann json library in C++.