c++读取/写入json

废话不多说, 都是自己写的
hello_json.json

{
    
    
    "listOfDict": [
        {
    
    
            "key1": "value1",
            "key2": "value2"
        },
        {
    
    
            "key1": "value1",
            "key2": "value2"
        }
    ]
}

main.cpp

//doc: https://github.com/nlohmann/json
# include <iostream>
# include"json.hpp" //download: https://github.com/nlohmann/json/releases/download/v3.9.1/json.hpp
# include <fstream>
using json = nlohmann::json;
int main(){
    
    
    //how to create a empty json object
    json j;

    //read a json file and write it to json object
    std::ifstream i("hello_json.json"); //# include <fstream>
    i >> j;

    //can we cout the json object?
    std::cout << j << std::endl; //yes we can

    //access the value of json object
    std::cout << j["listOfDict"][0]["key1"] << std::endl;

    //modify the value and check again
    j["listOfDict"][0]["key1"] = "new_value1";
    std::cout << j["listOfDict"][0]["key1"] << std::endl;

    //save the json object as a new json file and check again
    std::ofstream o("new_hello_json.json");
    o << j << std::endl;
    json new_j;
    std::ifstream new_i("new_hello_json.json"); //# include <fstream>
    new_i >> new_j;
    std::cout << new_j << std::endl;

    return 0;
}

最后获得的new_hello_json.json

{
    
    
    "listOfDict": [
        {
    
    
            "key1": "new_value1",
            "key2": "value2"
        },
        {
    
    
            "key1": "value1",
            "key2": "value2"
        }
    ]
}