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ZLIB(3)                                                                                              ZLIB(3)

       zlib - compression/decompression library

       [see zlib.h for full description]

       The  zlib  library  is a general purpose data compression library.  The code is thread safe, assuming
       that the standard library functions used are thread safe, such as  memory  allocation  routines.   It
       provides  in-memory compression and decompression functions, including integrity checks of the uncom-pressed uncompressed
       pressed data.  This version of the library supports only one compression method (deflation) but other
       algorithms may be added later with the same stream interface.

       Compression  can  be done in a single step if the buffers are large enough 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 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  com-pressed compressed
       pressed data, so the library should never crash even in the case of corrupted input.

       All  functions of the compression library are documented in the file zlib.h.  The distribution source
       includes examples of use of the library in the files example.c and minigzip.c, as well as other exam-ples examples
       ples in the examples/ directory.

       Changes to this version are documented in the file ChangeLog that accompanies the source.

       zlib is available in Java using the package:


       A  Perl interface to zlib, written by Paul Marquess (, is available at CPAN (Comprehen-sive (Comprehensive
       sive Perl Archive Network) sites, including:


       A Python interface to zlib, written by A.M. Kuchling (, is available in Python 1.5 and
       later versions:


       zlib is built into tcl:


       An experimental package to read and write files in .zip format, written on top of zlib by Gilles Vol-lant Vollant
       lant (, is available at:

     and also in the contrib/minizip directory of  the
              main zlib source distribution.

       The zlib web site can be found at:


       The  data  format used by the zlib library is described by RFC (Request for Comments) 1950 to 1952 in
       the files:

     (for the zlib header and trailer format)
     (for the deflate compressed data format)
     (for the gzip header and trailer format)

       Mark Nelson wrote an article about 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 zlib web site to verify that you have the latest version
       of zlib; otherwise, obtain the latest version and see if the problem still exists.  Please  read  the
       zlib FAQ at:


       before  asking  for  help.   Send questions and/or comments to, or (for the Windows DLL
       version) to Gilles Vollant (

       Version  1.2.5  Copyright  (C)  1995-2010  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 zlib was
       defined by Phil Katz.  The deflate and zlib specifications were written by L. Peter Deutsch.   Thanks
       to  all  the  people  who  reported  problems and suggested various improvements in zlib; who are too
       numerous to cite here.

       UNIX manual page by R. P. C. Rodgers, U.S. National Library of Medicine (

                                                 19 Apr 2010                                         ZLIB(3)

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