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.TH ZLIB 3 "18 July 2005"
zlib \- compression/decompression library
.I zlib.h
for full description]
.I zlib
library is a general purpose data compression library.
The code is thread safe.
It provides in-memory compression and decompression functions,
including integrity checks of the uncompressed data.
This version of the library supports only one compression method (deflation)
but other algorithms will be added later
and will have the same stream interface.
Compression can be done in a single step if the buffers are large enough
(for example if an input file is mmap'ed),
or can be done by repeated calls of the compression function.
In the latter case,
the application must provide more input and/or consume the output
(providing more output space) before each call.
The library also supports reading and writing files in
.IR gzip (1)
(.gz) format
with an interface similar to that of stdio.
The library does not install any signal handler.
The decoder checks the consistency of the compressed data,
so the library should never crash even in case of corrupted input.
All functions of the compression library are documented in the file
.IR zlib.h .
The distribution source includes examples of use of the library
in the files
.I example.c
.IR minigzip.c .
Changes to this version are documented in the file
.I ChangeLog
that accompanies the source,
and are concerned primarily with bug fixes and portability enhancements.
A Java implementation of
.I zlib
is available in the Java Development Kit 1.1:
A Perl interface to
.IR zlib ,
written by Paul Marquess (,
is available at CPAN (Comprehensive Perl Archive Network) sites,
A Python interface to
.IR zlib ,
written by A.M. Kuchling (,
is available in Python 1.5 and later versions:
.I zlib
binding for
.IR tcl (1),
written by Andreas Kupries (,
is availlable at:
An experimental package to read and write files in .zip format,
written on top of
.I zlib
by Gilles Vollant (,
is available at:
and also in the
.I contrib/minizip
directory of the main
.I zlib
web site.
.I zlib
web site can be found at either of these locations:
The data format used by the zlib library is described by RFC
(Request for Comments) 1950 to 1952 in the files:
.IP (concerning zlib format)
.br (concerning deflate format)
.br (concerning gzip format)
These documents are also available in other formats from:
Mark Nelson ( wrote an article about
.I zlib
for the Jan. 1997 issue of Dr. Dobb's Journal;
a copy of the article is available at:
Before reporting a problem,
please check the
.I zlib
web site to verify that you have the latest version of
.IR zlib ;
obtain the latest version and see if the problem still exists.
Please read the
.I zlib
FAQ at:
before asking for help.
Send questions and/or comments to,
or (for the Windows DLL version) to Gilles Vollant (
Version 1.2.3
Copyright (C) 1995-2005 Jean-loup Gailly (
and Mark Adler (
This software is provided "as-is,"
without any express or implied warranty.
In no event will the authors be held liable for any damages
arising from the use of this software.
See the distribution directory with respect to requirements
governing redistribution.
The deflate format used by
.I zlib
was defined by Phil Katz.
The deflate and
.I zlib
specifications were written by L. Peter Deutsch.
Thanks to all the people who reported problems and suggested various
improvements in
.IR zlib ;
who are too numerous to cite here.
UNIX manual page by R. P. C. Rodgers,
U.S. National Library of Medicine (
.\" end of man page