# phpman > man > zlib(3)

[ZLIB(3)](https://www.chedong.com/phpMan.php/man/ZLIB/3/markdown)                               Library Functions Manual                               [ZLIB(3)](https://www.chedong.com/phpMan.php/man/ZLIB/3/markdown)



## NAME
       zlib - compression/decompression library

## SYNOPSIS
       [see _zlib.h_ for full description]

## DESCRIPTION
       The _zlib_ library is a general purpose data compression library.  The code is thread safe, as‐
       suming 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 uncompressed 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)](https://www.chedong.com/phpMan.php/man/gzip/1/markdown) (.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 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   _test/example.c_   and
       _test/minigzip.c,_ as well as other examples in the _examples/_ directory.

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

       _zlib_  is built in to many languages and operating systems, including but not limited to Java,
       Python, .NET, PHP, Perl, Ruby, Swift, and Go.

       An experimental package to read and write files in the .zip format, written on top of _zlib_ by
       Gilles Vollant (<info@winimage.com>), is available at:

              <http://www.winimage.com/zLibDll/minizip.html> and also in the _contrib/minizip_ directory
              of the main _zlib_ source distribution.

## SEE ALSO
       The _zlib_ web site can be found at:

              <http://zlib.net/>

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

              <http://tools.ietf.org/html/rfc1950> (for the zlib header and trailer format)
              <http://tools.ietf.org/html/rfc1951> (for the deflate compressed data format)
              <http://tools.ietf.org/html/rfc1952> (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:

              <http://marknelson.us/1997/01/01/zlib-engine/>

## REPORTING PROBLEMS
       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:

              <http://zlib.net/zlib_faq.html>

       before asking for help.  Send questions and/or comments to <zlib@gzip.org>, or (for the Windows
       DLL version) to Gilles Vollant (<info@winimage.com>).

## AUTHORS AND LICENSE
       Version 1.2.11

       Copyright (C) 1995-2017 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.

       Permission is granted to anyone to use this software for any  purpose,  including  commercial
       applications,  and  to alter it and redistribute it freely, subject to the following restric‐
       tions:

       1. The origin of this software must not be misrepresented; you must not claim that you  wrote
          the  original  software.  If  you use this software in a product, an acknowledgment in the
          product documentation would be appreciated but is not required.

       2. Altered source versions must be plainly marked as such, and must not be misrepresented  as
          being the original software.

       3. This notice may not be removed or altered from any source distribution.

       Jean-loup Gailly        Mark Adler
       <jloup@gzip.org>          <madler@alumni.caltech.edu>

       The  deflate  format  used by _zlib_ was defined by Phil Katz.  The deflate and _zlib_ specifica‐
       tions 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
       (<rodgers@nlm.nih.gov>).



                                             15 Jan 2017                                     [ZLIB(3)](https://www.chedong.com/phpMan.php/man/ZLIB/3/markdown)