JsonApiPlay.cpp

// JsonApi.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>
#include "curl/curl.h"
#include "JsonApi.h"
#include "json.hpp"

using namespace std;


// for convenience
using json = nlohmann::json;

int main()
{   
    CallApi();
}

/*
    Because curl resturn a curl resource, this is to accumulate in a string the response.
    It is used as a callback.
*/
size_t WriteCallback(char* contents, size_t size, size_t nmemb, void* userp)
{
    ((std::string*)userp)->append((char*)contents, size * nmemb);
    return size * nmemb;
}

void ProcessJson(json json)
{
    int completed = 0;
    int notCompleted = 0;

    //C++ 11 supports for like in c# and java 
    for (auto it : json)
    {
        // "it" is of type json::reference and has no key() member
        // std::cout << "value: " << it["completed"] << '\n';

        if (it["completed"] == true)
        {
            completed++;
        }

        if (it["completed"] == false)
        {
            notCompleted++;
        }
        // notCompleted = it.size() - completed; not working as expected
    }
    cout << "Completed TODOs: " << completed << "\n";
    cout << "Not completed TODOs: " << notCompleted << "\n";
}

int CallApi()
{
    auto url = "https://jsonplaceholder.typicode.com/todos";
    CURL* req = curl_easy_init();
    CURLcode res;

    std::string readBuffer;
    if (req)
    {
        curl_easy_setopt(req, CURLOPT_URL, url);
        curl_easy_setopt(req, CURLOPT_FOLLOWLOCATION, 1L);
        curl_easy_setopt(req, CURLOPT_WRITEFUNCTION, WriteCallback);
        curl_easy_setopt(req, CURLOPT_WRITEDATA, &readBuffer);
        res = curl_easy_perform(req);
        if (res != CURLE_OK)
        {
            fprintf(stderr, "curl_easy_operation() failed : %s\n", curl_easy_strerror(res));
        }
        auto j = json::parse(readBuffer);
        ProcessJson(j);
    }
    curl_easy_cleanup(req); 
    return 0;
}

// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

// Tips for Getting Started: 
//   1. Use the Solution Explorer window to add/manage files
//   2. Use the Team Explorer window to connect to source control
//   3. Use the Output window to see build output and other messages
//   4. Use the Error List window to view errors
//   5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
//   6. In the future, to open this project again, go to File > Open > Project and select the .sln file

JsonApiPlay.h

#pragma once

int CallApi();

Completed TODOs: 90
Not completed TODOs: 110
Press any key to continue . . .