gzdeflate

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

gzdeflate — Comprime una stringa

Descrizione

gzdeflate(string $data, int $level = -1, int $encoding = ZLIB_ENCODING_RAW): string|false

Questa funzione comprime la stringa data utilizzando il formato dati DEFLATE.

Per i dettagli sull'algoritmo di compressione DEFLATE, vedere il documento "» DEFLATE Compressed Data Format Specification version 1.3" (RFC 1951).

Elenco dei parametri

data: I dati da comprimere.
level: Il livello di compressione. Varia tra 0 per nessuna compressione fino a 9 per la compressione massima. Se non viene specificato, il livello di compressione di default sarà quello di default della libreria zlib.
encoding: Una delle costanti ZLIB_ENCODING_*.

Valori restituiti

La stringa compressa o false in caso di errore.

Esempi

Example #1 Esempio di gzdeflate()

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

Vedere anche:

gzinflate() - Inflate a deflated string
gzcompress() - Comprime una stringa
gzuncompress() - Decomprime una stringa compressa
gzencode() - Crea una stringa compressa con gzip

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User Contributed Notes 3 notes

down

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

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