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example.json

Code Block

language	js

// Configuration options
{
    // Default encoding for text
    "encoding" : "UTF-8",
    // Plug-ins loaded at start-up
    "plug-ins" : [
        "python",
        "c++",
        "ruby"
        ],
    // Tab indent size
    "indent" : { "length" : 3, "use_space": true }
}

example.cpp

Code Block

language	cpp
title	example.cpp
linenumbers	true
collapse	true

#include <stdlib.h>
#include <fstream>
// This is the JSON header
#include "json/json.h"
using namespace std;
int main(int argc, char **argv)
{
    ifstream ifs("example.json");
    Json::Value root;   // will contains the root value after parsing.
    Json::Reader reader;
    bool parsingSuccessful = reader.parse(ifs, root );
    if ( !parsingSuccessful )
    {
        // report to the user the failure and their locations in the document.
        std::cout  << "Failed to parse configuration\n"
                   << reader.getFormattedErrorMessages();
        return 0;
    }
// Get the value of the member of root named 'encoding', return 'UTF-8' if there is no
// such member.
    std::string encoding = root.get("encoding", "UTF-8" ).asString();
// Get the value of the member of root named 'encoding', return a 'null' value if
// there is no such member.
    const Json::Value plugins = root["plug-ins"];
    cout << "plug-ins : ";
    for ( int index = 0; index < plugins.size(); ++index )  // Iterates over the sequence elements.
        cout << plugins[index].asString() << ","; 
    cout << endl;
    //setIndentLength( root["indent"].get("length", 3).asInt() );
    //setIndentUseSpace( root["indent"].get("use_space", true).asBool() );
// ...
// At application shutdown to make the new configuration document:
// Since Json::Value has implicit constructor for all value types, it is not
// necessary to explicitly construct the Json::Value object:
    root["encoding"] = "UTF-16";
    root["indent"]["length"] = 5;
    root["indent"]["use_space"] = 0;
    Json::StyledWriter writer;
// Make a new JSON document for the configuration. Preserve original comments.
    std::string outputConfig = writer.write( root );
// You can also use streams.  This will put the contents of any JSON
// stream at a particular sub-value, if you'd like.
    std::cin >> root["subtree"];
// And you can write to a stream, using the StyledWriter automatically.
    std::cout << root;
    return 0;
}

compile
1. g++ -o example example.cpp jsoncpp.cpp -I. -DJSON_IS_AMALGAMATION
실행
1. ./example

jsonCPP 는 std::cin stream 에서 json 데이타를 입력받을수 있고 위 예제는 subtree 라는 value 를 요구하므로 아래와 같은 json data 를 입력하고 Ctrl-D 를 누르면 된다.

Code Block
./example plug-ins : python,c++,ruby, { "name": "value", "arrary": { "age": 99, "ar": [ 1, 2, 3, 4 ] } } // Configuration options

결과

Code Block

collapse	true

{// Default encoding for text

        "encoding" : "UTF-16",// Tab indent size

        "indent" : 
        {
                "length" : 5,
                "use_space" : 0
        },// Plug-ins loaded at start-up

        "plug-ins" : [ "python", "c++", "ruby" ],
        "subtree" : 
        {
                "arrary" : 
                {
                        "age" : 99,
                        "ar" : [ 1, 2, 3, 4 ]
                },
                "name" : "value"
        }
}

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