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(PHP 4 >= 4.0.1, PHP 5)

gzuncompressDekomprimiert einen komprimierten String


string gzuncompress ( string $data [, int $length = 0 ] )

Diese Funktion dekomprimiert einen komprimierten String.



Mit gzcompress() komprimierte Daten


Die maximale Länge der dekodierten Daten.


Die ursprünglichen nicht komprimierten Daten oder FALSE bei Fehlern.

Die Funktion gibt einen Fehler zurück wenn die unkomprimierten Daten mehr als 32768 mal so lang sind wie die komprimierte Eingabe oder länger als mit dem optionalen Parameter length angegeben.


Beispiel #1 gzuncompress() Beispiel

gzcompress('Compress me'9);
$uncompressed gzuncompress($compressed);

Siehe auch

6 BenutzerBeiträge:
- Beiträge aktualisieren...
MagicalTux at php dot net
31.12.2010 22:36
Hi, I got an alternative for those zipped strings that gzuncompress() cannot extract.

It is a bit better than previous options as it do not create any temporary files, but it has to encode the string in base64, meaning it won't be as fast as a native equivalent (which is probably going to be gzdecode())

if (!function_exists('gzdecode')) {
gzdecode($string) { // no support for 2nd argument
return file_get_contents('compress.zlib://data:who/cares;base64,'. base64_encode($string));
24.08.2009 4:07
One way to uncompress zlib-compressed data that is in a file without first reading in the file and then gzuncompressing it (maybe you have memory problems doing it that way) is to compile the zpipe.c program from zlib ( )...

on linux, etc:

# gcc -lz -o zpipe zpipe.c

# cp zpipe /usr/local/bin

Then do this


= shell_exec("cat $compressed_file | zpipe -d");

heavyccasey at gmail dot com
8.11.2007 5:30
Note that gzuncompress() may not decompress some compressed strings and return a Data Error.

The problem could be that the outside compressed string has a CRC32 checksum at the end of the file instead of Adler-32, like PHP expects.

function gzuncompress_crc32($data) {
$f = tempnam('/tmp', 'gz_fix');
file_put_contents($f, "\x1f\x8b\x08\x00\x00\x00\x00\x00" . $data);
file_get_contents('compress.zlib://' . $f);
gabriel at bumpt dot n-et
18.09.2007 0:08
To uncompress in PHP a string that has been compressed using MySQL's COMPRESS() function, you need to discard the first four bytes of the binary data:


   * Example:
   * insert into mytable (myfield, ...) values (COMPRESS('foobar'), ...)
   * then:
$compressed = // myfield from mytable where...
   * then:
$uncompressed = gzuncompress(substr($compressed, 4));

Of course, you can use MySQL's UNCOMPRESS() function.
I was just providing an alternate method.
emanuele at fondani dot it
25.11.2006 12:21
Note that the manual states that the input parameter must be a string compressed with gzcompress(), so it is not guaranteed that it will compress ANY zlib compressed string.
I realized this while decompressing some compressed string in a pdf file. The gzuncompress() function produces a data error, but the string can be successfully decompressed with other zlib decompressors.

More info here:
chappy at citromail dot hu
13.04.2006 16:47
Reading an ID3v2.3+ tag it is versy useful, because these tag's frames might be compressed. Zlib compressed frame layout (ID3v2.3):

Descriptior                                                    Size
Frame id:                                                      4 bytes
Frame size (full frame size - frameheader size): 4 bytes
Frame flags:                                                  2 bytes
    The 2nd byte's 7th bit must be 1 (e.g.: %1xy00000)
Frame content decrompessed size:                   4 bytes
Compressed string                                          described in 'frame size'

="[read from a mp3 file]";

'Error whil uncrompessing frame data<br>';

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