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CL. Zlib Compression Functions
This module enables you to transparently read and write
gzip (.gz) compressed files, through versions of most of
the filesystem functions
which work with gzip-compressed files (and uncompressed files,
too, but not with sockets).
Note:
Version 4.0.4 introduced a fopen-wrapper for .gz-files, so that
you can use a special 'zlib:' URL to access compressed files
transparently using the normal f*() file access functions if you
prepend the filename or path with a 'zlib:' prefix when calling
fopen().
In version 4.3.0, this special prefix has been changed to 'zlib://'
to prevent ambiguities with filenames containing ':'.
This feature requires a C runtime library that provides the
fopencookie() function. To my current
knowledge the GNU libc is the only library that provides
this feature.
This module uses the functions of zlib
by Jean-loup Gailly and Mark Adler. You have to use a zlib
version >= 1.0.9 with this module.
Zlib support in PHP is not enabled by default. You will need to
configure PHP --with-zlib[=DIR]
The windows version of PHP has built in
support for this extension. You do not need to load any additional
extension in order to use these functions. Note:
Builtin support for zlib on Windows is available with PHP 4.3.0.
The behaviour of these functions is affected by settings in php.ini.
The zlib extension offers the option to transparently compress
your pages on-the-fly, if the requesting browser supports
this. Therefore there are three options in the configuration file php.ini.
Table 1. Zlib Configuration Options | Name | Default | Changeable | Changelog |
|---|
| zlib.output_compression | "0" | PHP_INI_ALL | Available since PHP 4.0.5. | | zlib.output_compression_level | "-1" | PHP_INI_ALL | Available since PHP 4.3.0. | | zlib.output_handler | "" | PHP_INI_ALL | Available since PHP 4.3.0. |
For further details and definitions of the
PHP_INI_* constants, see the Appendix H.
Here's a short explanation of
the configuration directives.
- zlib.output_compression
boolean/integer
Whether to transparently compress pages. If this option is set
to "On" in php.ini or the Apache configuration, pages are
compressed if the browser sends an "Accept-Encoding: gzip" or
"deflate" header. "Content-Encoding: gzip" (respectively
"deflate") and "Vary: Accept-Encoding" headers are added to
the output.
This option also accepts integer values instead of boolean
"On"/"Off", using this you can set the output buffer size
(default is 4KB).
Note:
output_handler must be
empty if this is set 'On' ! Instead you must use zlib.output_handler.
- zlib.output_compression_level
integer
Compression level used for transparent output compression.
- zlib.output_handler
string
You cannot specify additional output handlers if zlib.output_compression
is activated here. This setting does the same as
output_handler but in a different order.
This extension has no resource types defined.
The constants below are defined by this extension, and
will only be available when the extension has either
been compiled into PHP or dynamically loaded at runtime.
This example opens a temporary file and writes a test string
to it, then it prints out the content of this file twice.
Example 1. Small Zlib Example
<?php
$filename = tempnam('/tmp', 'zlibtest') . '.gz';
echo "<html>\n<head></head>\n<body>\n<pre>\n";
$s = "Only a test, test, test, test, test, test, test, test!\n";
// open file for writing with maximum compression
$zp = gzopen($filename, "w9");
// write string to file
gzwrite($zp, $s);
// close file
gzclose($zp);
// open file for reading
$zp = gzopen($filename, "r");
// read 3 char
echo gzread($zp, 3);
// output until end of the file and close it.
gzpassthru($zp);
gzclose($zp);
echo "\n";
// open file and print content (the 2nd time).
if (readgzfile($filename) != strlen($s)) {
echo "Error with zlib functions!";
}
unlink($filename);
echo "</pre>\n</body>\n</html>\n";
?>
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- Table of Contents
- gzclose -- Close an open gz-file pointer
- gzcompress -- Compress a string
- gzdeflate -- Deflate a string
- gzencode -- Create a gzip compressed string
- gzeof -- Test for end-of-file on a gz-file pointer
- gzfile -- Read entire gz-file into an array
- gzgetc -- Get character from gz-file pointer
- gzgets -- Get line from file pointer
- gzgetss --
Get line from gz-file pointer and strip HTML tags
- gzinflate -- Inflate a deflated string
- gzopen -- Open gz-file
- gzpassthru --
Output all remaining data on a gz-file pointer
- gzputs -- Alias of gzwrite()
- gzread -- Binary-safe gz-file read
- gzrewind -- Rewind the position of a gz-file pointer
- gzseek -- Seek on a gz-file pointer
- gztell -- Tell gz-file pointer read/write position
- gzuncompress -- Uncompress a compressed string
- gzwrite -- Binary-safe gz-file write
- readgzfile -- Output a gz-file
- zlib_get_coding_type -- Returns the coding type used for output compression
Copyright © 1997 - 2007 by the PHP Documentation Group. This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later. A copy of the Open Publication License is distributed with this manual, the latest version is presently available at http://www.opencontent.org/openpub/.
Please see full copyright text at http://www.php.net/manual/en/copyright.php
Original version of the above documentation is available at http://www.php.net/manual/en/
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