@node ax_check_zlib
@unnumberedsec ax_check_zlib

@majorheading Synopsis

@smallexample
AX_CHECK_ZLIB([action-if-found], [action-if-not-found])
@end smallexample

@majorheading Description

This macro searches for an installed zlib library. If nothing was
specified when calling configure, it searches first in /usr/local and
then in /usr, /opt/local and /sw. If the --with-zlib=DIR is specified,
it will try to find it in DIR/include/zlib.h and DIR/lib/libz.a. If
--without-zlib is specified, the library is not searched at all.

If either the header file (zlib.h) or the library (libz) is not found,
shell commands 'action-if-not-found' is run. If 'action-if-not-found' is
not specified, the configuration exits on error, asking for a valid zlib
installation directory or --without-zlib.

If both header file and library are found, shell commands
'action-if-found' is run. If 'action-if-found' is not specified, the
default action appends '-I$@{ZLIB_HOME@}/include' to CPFLAGS, appends
'-L$ZLIB_HOME@}/lib' to LDFLAGS, prepends '-lz' to LIBS, and calls
AC_DEFINE(HAVE_LIBZ). You should use autoheader to include a definition
for this symbol in a config.h file. Sample usage in a C/C++ source is as
follows:

@smallexample
  #ifdef HAVE_LIBZ
  #include <zlib.h>
  #endif /* HAVE_LIBZ */
@end smallexample

@majorheading Source Code

Download the
@uref{http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_check_zlib.m4,latest
version of @file{ax_check_zlib.m4}} or browse
@uref{http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=history;f=m4/ax_check_zlib.m4,the
macro's revision history}.

@majorheading License

@w{Copyright @copyright{} 2008 Loic Dachary @email{loic@@senga.org}} @* @w{Copyright @copyright{} 2010 Bastien Chevreux @email{bach@@chevreux.org}}

This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
Public License for more details.

You should have received a copy of the GNU General Public License along
with this program. If not, see <https://www.gnu.org/licenses/>.

As a special exception, the respective Autoconf Macro's copyright owner
gives unlimited permission to copy, distribute and modify the configure
scripts that are the output of Autoconf when processing the Macro. You
need not follow the terms of the GNU General Public License when using
or distributing such scripts, even though portions of the text of the
Macro appear in them. The GNU General Public License (GPL) does govern
all other use of the material that constitutes the Autoconf Macro.

This special exception to the GPL applies to versions of the Autoconf
Macro released by the Autoconf Archive. When you make and distribute a
modified version of the Autoconf Macro, you may extend this special
exception to the GPL to apply to your modified version as well.