deflate_init
(PHP 7)
deflate_init — Initialize an incremental deflate context
Description
$encoding
[, array $options
= array()
] ) : resource
Initializes an incremental deflate context using the specified
encoding
.
Note that the window option here only sets the window size
of the algorithm, differently from the zlib filters where the same parameter
also sets the encoding to use; the encoding must be set with the
encoding
parameter.
Limitation: there is currently no way to set the header information on a GZIP compressed stream, which are set as follows: GZIP signature (\x1f\x8B); compression method (\x08 == DEFLATE); 6 zero bytes; the operating system set to the current system (\x00 = Windows, \x03 = Unix, etc.)
Parameters
-
encoding
-
One of the
ZLIB_ENCODING_*
constants. -
options
-
An associative array which may contain the following elements:
- level
-
The compression level in range -1..9; defaults to -1.
- memory
-
The compression memory level in range 1..9; defaults to 8.
- window
-
The zlib window size (logarithmic) in range 8..15; defaults to 15.
- strategy
-
One of
ZLIB_FILTERED
,ZLIB_HUFFMAN_ONLY
,ZLIB_RLE
,ZLIB_FIXED
orZLIB_DEFAULT_STRATEGY
(the default). - dictionary
-
A string or an array of strings of the preset dictionary (default: no preset dictionary).
Errors/Exceptions
If an invalid option is passed to options
or the
context couldn't be created, an error of level E_WARNING
is generated.
See Also
- deflate_add() - Incrementally deflate data
- inflate_init() - Initialize an incremental inflate context
English translation
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Document created the 30/01/2003, last modified the 26/10/2018
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References
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