gzdeflate

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

gzdeflate — Deflate a string

说明

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).

参数

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.

返回值

The deflated string or false if an error occurred.

示例

示例 #1 gzdeflate() example

<?php
$compressed = gzdeflate('Compress me', 9);
echo $compressed;
?>

参见

gzinflate() - Inflate a deflated string
gzcompress() - Compress a string
gzuncompress() - Uncompress a compressed string
gzencode() - Create a gzip compressed string

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用户贡献的备注 3 notes

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giunta dot gaetano at sea-aeroportimilano dot it ¶

18 years ago

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

down

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.

down

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%
-------------------------------------------------------------------------------------------------------------------