Learning Poco: Zip Files

In this tutorial, we will zip files into a single archive file by using Poco::Zip::Compress. We do not handle directories here but you may add this functionality by referencing the previous tutorial about listing directories recursively.

The Poco here stands for the POCO C++ libraries and is not to be confused with Plain Old CLR Object.

Create a file my_zip.cc with the following lines:

#include <Poco/File.h>
#include <Poco/Path.h>
#include <Poco/Zip/Compress.h>
#include <iostream>
#include <fstream>

using namespace Poco;
using namespace Poco::Zip;
using namespace std;

int main(int argc, char **argv)
{
  if (argc < 2)
  {
    cout << "Usage: " << argv[0] 
    << " filename.zip [files...]" << endl;
    return -1;
  }

  ofstream out(argv[1], ios::binary);
  Compress c(out, true);
  for (int i = 2; i < argc; i++)
  {
    File f(argv[i]);
    if (f.exists())
    {
      Path p(f.path());
      if (f.isDirectory())
      {
        cout << "Ignore directory " << f.path() << endl;
      }
      else if (f.isFile())
      {
        cout << "Add file " << f.path() << endl;
        c.addFile(p, p.getFileName());
      }
    }
  }
  c.close();
  out.close();

  return 0;
}

Compile it and run:

$ g++ -o my_zip my_zip.cc -lPocoZip
$ ./my_zip
Usage: ./my_zip filename.zip [files...]
$ ./my_zip some.zip my_zip my_zip.cc
Add file my_zip
Add file my_zip.cc

You may unzip the file produced to check its validity.

Note that in order to handle (most importantly, recognize) directories correctly, we have to use File instead of Path, because Path::isDirectory only checks according to the string provided rather than the actual file-system structure.

For example, if you have some directory called testdir, Path(“testdir”).isDirectory() will be false while Path(“testdir/”).isDirectory() will be true. So we have to use File::isDirectory here.

Related Articles

• Learning Poco: GET with HTTP
• Learning Poco: A simple HTTP server
• Learning Poco: Load XML Configuration
• Learning Poco: Getting started with threads
• Learning Poco: List directories recursively

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