Environment: Win98, VC 5.0

This article describes classes to zip and unzip files.  The classes use the gzip GNU source code (gzip-1.2.4a).  This is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License.  See the file COPYING included in the source code.

The target DLL exports two classes:

• CZip (for zipping files)
• CUnzip (for unzipping files)

Description:

A CZip or CUnzip object is built with a file name.  Then, the SwapSize() method must be called on that object (with one argument which is the target file name) in order to zip/unzip the file.  SwapSize() may throw a CZipException exception.  A message bound to the exception can be retrieved using the GetString() method.  Exceptions are thrown when:

• the source file does not exists or cannot be opened for reading
• the target file cannot be created (for example, this file already exists)
• the gzip code is returns an error;  in this case, the message bound to the exception contains the message returned by the gzip source code via stderr

To use CZip or CUnzip, do the following:

1. include czip.h in your project
2. link your project with zipdll.dll using zipdll.lib
3. move zipdll.dll to the same directory as your executable
   Note:  You can also dynamically link to zipdll.dll (I haven't tested that, though).

Here's an example of how to zip a file:

  try
  {
    CZip myFileToZip ("file_to_zip_name");
    myFileToZip.SwapSize ("file_zipped_name"); 
  } 
  catch (CZipException e) 
  {
    cout << "problem while zipping : " << e.GetString() << endl;
    delete pExcep; 
  } 

Notes:

1. The CZipped files can be unzipped using WinZip if its name doesn't have a ".zip" extension.  If the zipped file has a ".zip" extension, WinZip won't be able to open the file.

2. An archive constructed with WinZip can be extracted using a CUnzip object if it contains only a single file.

3. In order to know the error messages written by gzip code on stderr, a temp file is built and attached to stderr.  If this temp file cannot be built (no way to write to the current directory for example), the error messages from gzip code (if any) will not be known, but the zip/unzip operations can still be achieved.

Download:

CZip/CUnzip DLL source   czip_source.zip (99 KB)
Demo program   czip_demo.zip (3 KB)

Date Updated: 2 March 1999
Date Posted: 27 February 1999

Comments:

• How can add multiple files in one gz file with full path of every file - banner (2000/05/14)
• can we spawn on multiple floppy disks? - Mario (2000/01/18)
• CZIP is not compitable with PKZIP/PKUNZIP, any help? - keith liu (2000/01/13)
• Cool but, how to crypt or add a password - David LAFAY (1999/12/07)
• Cool, but How can I add or extract more then one file.? - Alex (1999/11/05)
• Tanx - Zodrak (1999/10/17)
• WinZip couldn't open the zip file! - Karim (1999/10/15)
• Good,Very Good. - guohong (1999/10/11)
• Using library in ATL - Jerrod Wetherill (1999/09/10)
• LZW license information - Paul D. (1999/09/09)
• It's fine. Can you give any information about .CAB Files - Vinod (1999/08/28)
• You are really great - Manoj Kumar K (MM soft tek) (1999/07/16)
• how about on NT - yang (1999/03/29)
• add more files to the archive - Xiaohua (1999/03/26)
• You may have to pay (cheap) royalties for using ZIP/UNZIP... - Brian Dixon (1999/03/05)
• Why it cannot be open with WinZip when it has a ".zip" extension? - sun jian (1999/03/03)

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