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Zlib Compression Functions

CLXXXVI. 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).

Notatka: 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 prefix the filename or path with zlib: when calling fopen(). This feature requires a C runtime library that provides the fopencookie() function. Up to now the GNU libc seems to be the only library that provides this feature.

In PHP 4.3.0, zlib: has been changed to compress.zlib:// to prevent ambiguities with filenames containing ':' characters. The fopencookie() function is not longer required. More information is available in the section about sekcja Compression Streams w Dodatek M.


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]

PHP w wersji dla systemów Windows posiada wbudowaną obsługę dla tego rozszerzenia. Nie trzeba ładować żadnych dodatkowych rozszerzeń aby korzystać z tych funkcji.

Notatka: Built-in support for zlib on Windows is available with PHP 4.3.0.

Konfiguracja uruchomieniowa

Na działanie tych funcji wpływają ustawienia zawarte w pliku 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.

Tabela 1. Zlib Configuration Options

zlib.output_compression"0"PHP_INI_ALLAvailable since PHP 4.0.5.
zlib.output_compression_level"-1"PHP_INI_ALLAvailable since PHP 4.3.0.
zlib.output_handler""PHP_INI_ALLAvailable since PHP 4.3.0.
Szczegóły i definicje dotyczące stałych PHP_INI_* znajdują się w rozdziale Dodatek G.

Oto krótkie wyjaśnienie dyrektyw konfiguracji.

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. In runtime, it can be set only before sending any output.

This option also accepts integer values instead of boolean "On"/"Off", using this you can set the output buffer size (default is 4KB).

Notatka: 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.

Typy zasobów

To rozszerzenie nie posiada żadnych rodzajów zasobów.

Stałe predefiniowane

Poniższe stałe są zdefiniowane w tym rozszerzeniu i stają się dostępne, gdy rozszerzenie jest dokompilowane do PHP, lub załadowane dynamicznie przy starcie.

FORCE_GZIP (integer)



This example opens a temporary file and writes a test string to it, then it prints out the content of this file twice.

Przykład 1. Small Zlib Example


= tempnam('/tmp', 'zlibtest') . '.gz';
$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

// open file for reading
$zp = gzopen($filename, "r");

// read 3 char
echo gzread($zp, 3);

// output until end of the file and close it.


// open file and print content (the 2nd time).
if (readgzfile($filename) != strlen($s)) {
"Error with zlib functions!";

Spis treści
gzclose -- Close an open gz-file pointer
gzcompress -- Compress a string
gzdecode -- Decodes a gzip compressed 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 dla 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