Json-cpp - how to initialize from string and get string value?

Greyshack picture Greyshack · Jun 29, 2015 · Viewed 50.8k times · Source

My code below crashes(Debug Error! R6010 abort() has been called). Can you help me? I'd also would like to know how to initialize the json object from a string value.

Json::Value obj;
obj["test"] = 5;
obj["testsd"] = 655;
string c = obj.asString();

Answer

Irineu Antunes picture Irineu Antunes · Jun 29, 2015

Hello it is pretty simple:

1 - You need a CPP JSON value object (Json::Value) to store your data

2 - Use a Json Reader (Json::Reader) to read a JSON String and parse into a JSON Object

3 - Do your Stuff :)

Here is a simple code to make those steps:

#include <stdio.h>
#include <jsoncpp/json/json.h>
#include <jsoncpp/json/reader.h>
#include <jsoncpp/json/writer.h>
#include <jsoncpp/json/value.h>
#include <string>

int main( int argc, const char* argv[] )
{

    std::string strJson = "{\"mykey\" : \"myvalue\"}"; // need escape the quotes

    Json::Value root;   
    Json::Reader reader;
    bool parsingSuccessful = reader.parse( strJson.c_str(), root );     //parse process
    if ( !parsingSuccessful )
    {
        std::cout  << "Failed to parse"
               << reader.getFormattedErrorMessages();
        return 0;
    }
    std::cout << root.get("mykey", "A Default Value if not exists" ).asString() << std::endl;
    return 0;
}

To compile: g++ YourMainFile.cpp -o main -l jsoncpp

I hope it helps ;)