Take care that that "PHP deflate" != "HTTP deflate".
The deflate encoding used in HTTP is actually zlib encoded.
This is what PHP functions return:
gzencode() == gzip
gzcompress() == zlib (aka. HTTP deflate)
gzdeflate() == *raw* deflate encoding
gzdeflate
(PHP 4 >= 4.0.4, PHP 5, PHP 7)
gzdeflate — Deflate a string
Descrierea
gzdeflate
( string
$data
, int $level = -1
, int $encoding = ZLIB_ENCODING_RAW
) : string|false
This function compresses the given string using the DEFLATE
data format.
For details on the DEFLATE compression algorithm see the document "» DEFLATE Compressed Data Format Specification version 1.3" (RFC 1951).
Parametri
-
data -
The data to deflate.
-
level -
The level of compression. Can be given as 0 for no compression up to 9 for maximum compression. If not given, the default compression level will be the default compression level of the zlib library.
-
encoding -
One of
ZLIB_ENCODING_*constants.
Valorile întoarse
The deflated string or false if an error occurred.
Exemple
Example #1 gzdeflate() example
<?php
$compressed = gzdeflate('Compress me', 9);
echo $compressed;
?>
A se vedea și
- gzinflate() - Inflate a deflated string
- gzcompress() - Compress a string
- gzuncompress() - Uncompress a compressed string
- gzencode() - Create a gzip compressed string
add a note
User Contributed Notes 10 notes
giunta dot gaetano at sea-aeroportimilano dot it ¶
18 years ago
anonymous at php dot net ¶
15 years ago
gzcompress produces longer data because it embeds information about the encoding onto the string. If you are compressing data that will only ever be handled on one machine, then you don't need to worry about which of these functions you use. However, if you are passing data compressed with these functions to a different machine you should use gzcompress.
dmitrysmirnovdeveloper at gmail dot com ¶
10 months ago
this is a benchmark test of gzdeflate (.txt file)
-------------------------------------------------------------------------------------------------------------------
Level ZLIB_ENCODING_RAW ZLIB_ENCODING_DEFLATE ZLIB_ENCODING_GZIP
-------------------------------------------------------------------------------------------------------------------
Level 0 7.22Mb (7574498 bytes) -0.0077% 7.22Mb (7574504 bytes) -0.0077% 7.22Mb (7574516 bytes) -0.0079%
Level 1 2.31Mb (2420570 bytes) 68.0407% 2.31Mb (2420576 bytes) 68.0406% 2.31Mb (2420588 bytes) 68.0405%
Level 2 2.18Mb (2287031 bytes) 69.8039% 2.18Mb (2287037 bytes) 69.8038% 2.18Mb (2287049 bytes) 69.8036%
Level 3 2.11Mb (2216241 bytes) 70.7385% 2.11Mb (2216247 bytes) 70.7384% 2.11Mb (2216259 bytes) 70.7383%
Level 4 2.01Mb (2110510 bytes) 72.1345% 2.01Mb (2110516 bytes) 72.1344% 2.01Mb (2110528 bytes) 72.1343%
Level 5 1.98Mb (2073133 bytes) 72.628% 1.98Mb (2073139 bytes) 72.6279% 1.98Mb (2073151 bytes) 72.6278%
Level 6 1.93Mb (2026592 bytes) 73.2425% 1.93Mb (2026598 bytes) 73.2424% 1.93Mb (2026610 bytes) 73.2423%
Level 7 1.93Mb (2019252 bytes) 73.3394% 1.93Mb (2019258 bytes) 73.3393% 1.93Mb (2019270 bytes) 73.3392%
Level 8 1.92Mb (2018354 bytes) 73.3513% 1.92Mb (2018360 bytes) 73.3512% 1.92Mb (2018372 bytes) 73.351%
Level 9 1.92Mb (2018354 bytes) 73.3513% 1.92Mb (2018360 bytes) 73.3512% 1.92Mb (2018372 bytes) 73.351%
-------------------------------------------------------------------------------------------------------------------
robin ¶
14 years ago
running 50000 repetitions on various content, i found that gzdeflate() and gzcompress() both performed equally fast regardless content and compression level, but gzinflate() was always about twice as fast as gzuncompress().
stockton at wowway dot com ¶
11 years ago
After some searching and experimentation I found that the output from this function cannot be 'inflated' with the objective c 'zlibInflate' wrapper for 'zlib' that is available at http://cocoadev.com/wiki/NSDataCategory but the output from gzcompress() can be. Thank you "anonymous at php dot net" and "tomas at slax dot org" for the clues. I hope this saves someone else the searching.
banditsmile at qq dot com ¶
9 years ago
start from php5.4.0 gzdeflate has the fastest speed and best zip rate.
http://3v4l.org/K2XAf
HUjuice ¶
8 years ago
The HTTP deflate is quite complicated.
The RFC7230, Sec 4.2.2 (https://tools.ietf.org/html/rfc7230#section-4.2.2) says:
«The "deflate" coding is a "zlib" data format [RFC1950] containing a "deflate" compressed data stream [RFC1951] that uses a combination of the Lempel-Ziv (LZ77) compression algorithm and Huffman coding.»
and, also:
«Note: Some non-conformant implementations send the "deflate" compressed data without the zlib wrapper.»
Since this function implements the RFC1951, the compliant encoding of a $payload should be:
gzcompress(gzdeflate($payload));
tomas at slax dot org ¶
16 years ago
gzcompress() is the same like gzdefflate(), it produces identical data and its speed is the same as well. The only difference is that gzcompress produces 6 bytes bigger result (2 extra bytes at the beginning and 4 extra bytes at the end).
denis dot noessler at red-at dot de ¶
21 years ago
if you have compressed data which is greater than 2 MB (system dependent), you will receive a buffer error by calling the function gzinflate().
be sure to to compress your data by a lower compression level, like 1.
i.e.: gzdeflate($sData, 1);
