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deflate_init

(PHP 7, PHP 8)

deflate_init — Initialize an incremental deflate context

说明

deflate_init(int $encoding, array|object $options = []): DeflateContext|false

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.)

参数

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. zlib changes a window size of 8 to 9, and as of zlib 1.2.8 fails with a warning, if a window size of 8 is requested for ZLIB_ENCODING_RAW or ZLIB_ENCODING_GZIP.

strategy

One of ZLIB_FILTERED, ZLIB_HUFFMAN_ONLY, ZLIB_RLE, ZLIB_FIXED or ZLIB_DEFAULT_STRATEGY (the default).

dictionary

A string or an array of strings of the preset dictionary (default: no preset dictionary).

返回值

Returns a deflate context resource (zlib.deflate) on success, 或者在失败时返回 false.

错误／异常

If an invalid option is passed to options or the context couldn't be created, an error of level E_WARNING is generated.

更新日志

版本 说明
8.0.0 On success, this function returns a DeflateContext instance now; previously, a resource was returned.

参见