'Zip' 'unzip' Logic ???

[XNikon]

Hello All:

I've always been fascinated by the technique of 'zip'ing files. Anyone knows the logic of 'zip'ing and 'unzip'ing ?? I mean, if I decide try to write a simple program 4 zipping / unzipping, would it be too hard?? Any props on the logic of zipping, unzipping are appreciated.

Thank u.

[phishphreek]

AFAIK: "zipping" and "unzipping" files are other words for compression and decompression.

there is pleny of info out there on file compression and decompression. there are many different techniques. you might have better luck searching google for compression techniques.

http://www.google.com/search?hl=en&l...ion+techniques

thats a start for you

[Negative]

Here's a nice little PDF explaining the basics.

[bluthund]

Negative, I have to disagree with you on this one, at least the link to
the Tutorials Forum. I typed in "zip files, zipping, compression, decompression, unzipping",
and guess what....

...zip...zilch...nada...nix.

Yes, a google search is definitely preferred, the database is much wider and deeper. One does have to be careful about reflexively referring to AO's tutorial database. It's not that big.

[Negative]

LOL... The link to the Tutorials Index is in my signature... it shows up in all my posts
The link for XNikon is in my post....

[bluthund]

Oops...*flagellates himself with banana peels*...definitely, slightly off target.

[mjk]

LOL bluthund

Anyways, if you want to write a simple program for zipping and unzipping, you might want to check out Python. There's a module for manipulating files with the zip format. Here's a quote from Python documentation:

7.18 zipfile -- Work with ZIP archives

New in version 1.6.

The ZIP file format is a common archive and compression standard. This module provides tools to create, read, write, append, and list a ZIP file. Any advanced use of this module will require an understanding of the format, as defined in PKZIP Application Note.

This module does not currently handle ZIP files which have appended comments, or multi-disk ZIP files.

The available attributes of this module are:


exception error
The error raised for bad ZIP files.

class ZipFile
The class for reading and writing ZIP files. See ``ZipFile Objects'' (section 7.18.1) for constructor details.

class PyZipFile
Class for creating ZIP archives containing Python libraries.

class ZipInfo( [filename[, date_time]])

Class used the represent infomation about a member of an archive. Instances of this class are returned by the getinfo() and infolist() methods of ZipFile objects. Most users of the zipfile module will not need to create these, but only use those created by this module. filename should be the full name of the archive member, and date_time should be a tuple containing six fields which describe the time of the last modification to the file; the fields are described in section 7.18.3, ``ZipInfo Objects.''

is_zipfile( filename)

Returns True if filename is a valid ZIP file based on its magic number, otherwise returns False. This module does not currently handle ZIP files which have appended comments.

ZIP_STORED
The numeric constant for an uncompressed archive member.

ZIP_DEFLATED
The numeric constant for the usual ZIP compression method. This requires the zlib module. No other compression methods are currently supported.

See Also:

PKZIP Application Note
Documentation on the ZIP file format by Phil Katz, the creator of the format and algorithms used.

Info-ZIP Home Page
Information about the Info-ZIP project's ZIP archive programs and development libraries.

--------------------------------------------------------------------------------

Subsections
7.18.1 ZipFile Objects
7.18.2 PyZipFile Objects
7.18.3 ZipInfo Objects

There you go Check it out. If you don't know python, you should at least try it. I love it. Props to HTRegz for introducing me to it

www.python.org

mjk

[yuvraj]

Ya mjk is right about the python zip n unzip modules.( linked with the manipulating files with the zip format)

hey mjk is there anyway of zip n unzip modules in Assembly language. dont give ideas bout the sites. Just tell where can i get proper tutorial.

[XNikon]

hmm.. Lemme try 2 get my hands on Python