14. JSON

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1. jsoncpp 설치 - Python

jsoncpp 설치 방법 (C++ 프로젝트 디렉터리: C_CPP)jsoncpp 빌드 방법

git clone https://github.com/open-source-parsers/jsoncpp.git && \
  cd ./jsoncpp && \
  python ./amalgamate.py && \
  cd .. && \
  mv ./jsoncpp/dist/* ./C_CPP && \
  sudo rm -rf jsoncpp

g++ -std=c++17 메인소스이름.cpp jsoncpp.cpp -o 실행파일이름 && 실행파일이름
g++ -std=c++17 test.cpp jsoncpp.cpp -o test && ./test

2. JSON 파일 쓰기

InputOutput

#include <fstream>
#include <iostream>
#include <string>

#include "json/json.h"
using namespace std;
using namespace Json;

int main() {
    ofstream json_file;
    json_file.open("json_exam.json");

    Value main;
    main["Job1"] = "developer";
    main["Job2"] = "author";

    Value sub;
    sub["Sub1"] = "Sub1";
    sub["Sub2"] = "Sub2";
    main["SubItems"] = sub;
    main["Sub3"] = "blogger";

    StyledWriter writer;
    string str = writer.write(main);
    cout << str << endl
         << endl;

    json_file << writer.write(main);
    json_file.close();

    return 0;
}

{
   "Job1" : "developer",
   "Job2" : "author",
   "Sub3" : "blogger",
   "SubItems" : {
      "Sub1" : "Sub1",
      "Sub2" : "Sub2"
   }
}

3. JSON 파일 읽기

InputOutput

#include <fstream>
#include <iostream>
#include <string>

#include "json/json.h"
using namespace std;
using namespace Json;

int main() {
    ifstream json_dir("json_exam.json");
    Reader reader;
    Value value;

    bool is_parse = reader.parse(json_dir, value);

    if (is_parse == true) {
        cout << "Job1: " << value["Job1"] << endl;
        cout << "SubItems Sub1: " << value["SubItems"]["Sub1"] << endl;
    } else {
        cout << "JSON 파일을 읽을 수 없습니다." << endl;
    }

    return 0;
}

Job1: "developer"
SubItems Sub1: "Sub1"

4. JSON 배열 사용

InputOutput

#include <fstream>
#include <iostream>
#include <string>

#include "json/json.h"
using namespace std;
using namespace Json;

int main() {
    ofstream json_write;
    json_write.open("json_exam.json");

    Value root;
    root["Title"] = "Array Exam";

    Value array1;
    array1.append("C#");
    array1.append("C++");

    Value array2;
    array2.append("Q#");
    array2.append("Qt");

    root["Language"]["Sample1"] = array1;
    root["Language"]["Sample2"] = array2;

    json_write << root;
    json_write.close();

    ifstream json_open("json_exam.json");
    Reader reader;
    Value value;
    reader.parse(json_open, value);

    cout << value << endl
         << endl;

    for (auto i : value["Language"]["Sample1"])
        cout << "Language Sample1: " << i << endl;

    return 0;
}

{
  "Language" :
  {
    "Sample1" :
    [
      "C#",
      "C++"
    ],
    "Sample2" :
    [
      "Q#",
      "Qt"
    ]
  },
  "Title" : "Array Exam"
}

Language Sample1: "C#"
Language Sample1: "C++"

5. JSON 타입 선택 읽기

InputOutput

#include <fstream>
#include <iostream>
#include <string>

#include "json/json.h"
using namespace std;
using namespace Json;

int main() {
    ofstream json_write;
    json_write.open("json_exam.json");

    Value root;
    root["Title"] = "Convert Exam";
    root["IsJson"] = true;

    Value numbers;
    numbers["No1"] = 12;
    numbers["No2"] = 20.3;

    root["Array"]["Number"] = numbers;

    json_write << root;
    json_write.close();

    ifstream json_open("json_exam.json");
    Reader reader;
    Value value;
    reader.parse(json_open, value);

    cout << value["Array"]["Number"].get("No1", -1).asInt() << endl;
    cout << value["Array"]["Number"].get("No2", -1).asDouble() << endl;
    cout << value["Array"]["Number"].get("No1", "Empty").asString() << endl;
    cout << boolalpha << value.get("IsJson", false).asBool() << endl;

    return 0;
}

12
20.3
12
true

6. JSON 요소 크기 확인

InputOutput

#include <fstream>
#include <iostream>
#include <string>

#include "json/json.h"
using namespace std;
using namespace Json;

int main() {
    ifstream json_open("json_exam.json");
    Reader reader;
    Value value;
    reader.parse(json_open, value);

    cout << "Root 크기: " << value.size() << endl;
    cout << "Array 크기: " << value["Array"].size() << endl;
    cout << "Number 크기: " << value["Array"]["Number"].size() << endl;

    return 0;
}

Root 크기: 3
Array 크기: 1
Number 크기: 2

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