C++ でファイルをダウンロードする

#include <windows.h>

#include <cstdio>
#include <string>
#pragma comment(lib, "Urlmon.lib")

using namespace std;

int main() {
  // the URL from where the file will be downloaded
  string SourceURL = "https://picsum.photos/200/300.jpg";

  // destination file
  string DestinationFile = "DemoFile.jpg";

  // URLDownloadToFile returns S_OK on success
  if (S_OK == URLDownloadToFile(NULL, SourceURL.c_str(),
                                DestinationFile.c_str(), 0, NULL)) {
    printf("The file is successfully downloaded.");

    return 0;

  }

  else {
    printf("Download Failed");
    return -1;
  }
}

The file is successfully downloaded.

#pragma comment(lib, "urlmon.lib")
#include <urlmon.h>

#include <cstdio>
#include <iostream>
#include <string>
#define getURL URLOpenBlockingStreamA

using namespace std;

int main() {
  IStream* DemoStream;
  const char* SourceURL = "http://google.com";

  if (getURL(0, SourceURL, &DemoStream, 0, 0)) {
    cout << "An Error has occured.";
    cout << "Please Check the internet";
    cout << "Please Check the source URL.";
    return -1;
  }

  // this char array will be filled with bytes from the URL
  char DemoBuff[100];
  // keep appending the bytes to this string
  string DemoStr;
  unsigned long Bytes_Read;

  while (true) {
    DemoStream->Read(DemoBuff, 100, &Bytes_Read);
    if (0U == Bytes_Read) {
      break;
    }
    // appending and collecting to the string
    DemoStr.append(DemoBuff, Bytes_Read);
  };

  DemoStream->Release();
  cout << DemoStr << endl;
  return 0;
}